Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Experimental toxicology of formaldehyde (1987)
    Springer
    Journal of cancer research and clinical oncology 113 (1987), S. 305-309 
    Details
    ISSN: 1432-1335
    Keywords: Formaldehyde ; Mutagenicity ; Metabolism ; Biochemistry ; Carcinogenicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Formaldehyde is a reactive chemical which undergoes spontaneous reactions with various cellular constituents. Mutagenicity data may be interpreted on the background of this behavior. Mice are better able to reduce the irritating effect of formaldehyde than rats and to reduce their ventilation rate when formaldehyde acts on the respiratory tract. Subacute exposure of rats to concentrations higher than 2 ppm inhibits mucociliary clearance of the nasal epithelium and leads to progressive histological and ultrastructural lesions at this site. The occurrence of squamous cell carcinomas of the nasal epithelium of rats after 2 years inhalation of 14.3 ppm formaldehyde (CIIT study) is probably the result of chronic and recurrent local toxicity; this is supported by species differences in susceptibility to the tissue damaging and carcinogenic effect of formaldehyde (rat, mouse, hamster). Data on formaldehyde-DNA interaction further support the argument that a direct risk extrapolation from the formaldehyde effects in rats to those expected for man is not possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397713
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Myoadenylate deaminase deficiency: absence of correlation with exercise intolerance in 452 muscle biopsies (1987)
    Springer
    Journal of neurology 234 (1987), S. 385-389 
    Details
    ISSN: 1432-1459
    Keywords: Myoadenylate deaminase ; Histochemistry ; Biochemistry ; Neuromuscular diseases ; Exertional myalgia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A histochemical assay was routinely performed of myoadenylate deaminase (MAD) in muscle biopsy specimens. MAD was absent in 13 cases, i.e. 2.9% of the specimens. In 10 cases the deficiency was confirmed biochemically. The diagnoses in the 13 patients were: polyneuropathy (n=5), infantile spinal muscular atrophy (n=3), congenital myopathy with type 2 fibre atrophy, facioscapulohumeral myopathy, polymyositis, myotonic dystrophy and hyperornithinaemia with gyrate atrophy of the retina. In contrast, 35 unrelated patients presenting with exercise-related muscle cramps or pains showed normal histochemical MAD activity. The biopsy specimens in all of these patients were essentially normal and in none of them was the diagnosis of a neuromuscular disease made. The results failed to confirm the association of MAD deficiency with aches, cramps and pains or exertional myalgia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314082
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Theoretical study of water-pyridine complexes using intermolecular potentials (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 67-80 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Intermolecular potential functions have been used to determine the equilibrium structures of the water-pyridine complexes. The dimer and symmetrical 2:1 water pyridine systems have been studied. Three water models, ST2, TIPS2, and EMPWI have been combined with two different Lennard Jones nonbonded parameters and various charge distributions for the pyridine molecule to describe the systems. For the dimer, results show two distinguishable classes of preferential hydration sites, which are specific sites corresponding to hydrogen-bonded dimer and nonspecific sites located near the hydrophobic regions. Calculations performed on hydrogen-bonded symmetrical complexes show that the planar complex is generally less stable than the complex with water molecules perpendicular to the pyridine plane. For these complexes, the major factor that influences the hydrogen-bonded configurations is the choice of the water model. The importance of atomic charge distributions for the solute over the choice of potential parameters is pointed out. Finally, the effective lone pair representation on the aromatic nitrogen atom is shown to improve the hydrogen bond geometry and the stability of the complexes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080109
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Optimized method for the evaluation of the convolutionally distorted decay curves (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 95-106 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A nonlinear least squares procedure based on the Meiron method is described for the evaluation of the convolutionally distorted decay curves consisting of exponentials. Most of the special procedures are well known and the selected ones proved to be the most effective. Some new procedures are introduced to facilitate the evaluation work and literature data are analyzed as an example.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080202
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The ellipsoid algorithm as a method for the determination of polypeptide conformations from experimental distance constraints and energy minimization (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 132-141 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new method for constrained nonlinear optimization known as the ellipsoid algorithm is evaluated as a means of determining and refining the conformations of peptides. Advantages of the ellipsoid algorithm over conventional optimization methods include that it avoids many local minima that other methods would be trapped by, and that it is sometimes able to find optimum solutions in which the constraints are satisfied exactly. The dihedral angles about single bonds were used as variables to keep the dimensionality low (the rate of convergence decreases rapidly with increasing dimensionality of the problem). The method is evaluated on problems involving distance constraints, and for minimization of conformational energy functions. In an initial application, conformations consistent with an experimental set of NMR distance constraints were obtained in a problem involving 48 variable dihedral angles.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080205
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    An algorithm for construction of the molecular distance matrix (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 170-173 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A simple computer-oriented method is presented for constructing the (molecular) distance matrix. The distance matrix considered is the graph-theoretical (topological) distance matrix.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080209
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    On Madelung's constant (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 291-295 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080404
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Centrifugal distortions in molecules: An ab initio approach with application to ozone (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 307-312 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Our procedure for employing analytical gradients of ab initio potential energy hypersurfaces in the description of centrifugally distorted molecules is applied for the first time to an asymmetric top, namely ozone. Both single determinantal (HF/6-31G*) and analytically fitted multiconfigurational self-consistent field surfaces were utilized. The focus of the HF/6-31G* study is upon the centrifugal distortion pathway. Quartic centrifugal spectroscopic coefficients are obtained in both cases and are in reasonable agreement with experiment.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    The application of strictly localized geminals to the description of chemical bonds (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 436-441 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A theory is developed in which closed-shell molecules are viewed as systems of weakly interacting chemical bonds. Composite-particle creation operators obtained by an appropriate quasiparticle transformation are used to create the wave function of two-electron bonds. These quasiparticles are bosons, since they are composed of two electrons, but the total many-electron wave function is properly antisymmetric. The internal structure of the quasi-Bose-particles is affected by inductive interbond interactions. Delocalization and dispersion interactions between different bonds are neglected, thus the approach corresponds to a first-order many-body PT (Perturbation Theory) with a correlated, but fully localized, reference state. The whole formalism is developed ab initio. The nonorthogonality problem is handled by a biorthogonal formulation. To illustrate the effectiveness of the model, numerical calculations are reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080421
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Numerical calculation of eigenvalues for the Schrödinger equation. III (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 459-461 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A recently developed method for calculation of eigenvalues is applied to a four coupled oscillator system previously used to test more approximate methods. Analysis is presented to show how the present method scales for systems of two, three, and four coupled oscillator systems.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080425
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    The shape of molecular charge distributions: Group theory without symmetry (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 462-469 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A group theoretical framework is proposed for a detailed characterization of the shapes of electronic charge distributions of general, asymmetric molecules. The proposed shape groups are the homology and cohomology groups of charge density contour surfaces. These shape groups depend on two real parameters, the charge density value a for the contour and a curvature parameter b. The two-parameter family of various homology groups and cohomology groups of charge density contour surfaces is independent of the symmetry properties of the molecules and gives a concise description of the dominant shape characteristics. For any fixed parameter value b these groups may change only at specific charge density values, characteristic to the given molecule. On the other hand, for a fixed-charge density contour the group changes induced by a change in the curvature parameter b provide a description of the fine details of the shape of the electron density. The changes in the structure of these groups follow strict algebraic relations, that provide a quantitative measure for shape-similarity between various molecules. The two-parameter shape group method is an extension of an earlier method proposed for biochemical applications.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080426
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Computational aspects of master equation transformation in terms of moments (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 420-427 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The master equation describing the temporal evolution of a gaseous system in contact with a heat bath can be transformed into a system of linear, constant-coefficient, first-order differential equations of moments of the population distribution. While it has the advantage that populations are obtained directly from observables (moments), this system of equations is not too well-conditioned and unless precautions are taken, unsurmountable numerical problems appear. These are principally associated with manipulations (inversion and taking the exponential of a matrix) involving slightly modified Vandermonde matrices whose elements span a very wide range of orders of magnitude. This article discusses ways to avoid these pitfalls which consist principally of a suitable matrix normalization.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080419
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Application of the MuMATH computer algebra system to sets of first order kinetic equations of significance in chemistry (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 442-447 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Analytical solutions to systems of first order differential equations have long been available; however, they become so involved that they are seldom used. Numerical simulations are preferred in practice, although they produce bulky output that is difficult to interpret. Even worse, they are occasionally seriously in error owing to “stiffness” in the equations, intrinsic instability, or other pathological behavior. Computer algebra systems can handle the complicated manipulations that make the analytical solutions of first order kinetic systems inconvenient and can serve as a check on numerical simulations. We show applications of the small MuMATH(R) computer algebra package to a variety of first-order process, including relaxation kinetics and the analysis of stability of steady states in nonlinear kinetic systems.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080422
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    On the SCF calculation of excited states: Singlet states in the two-electron problem (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 454-458 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The problem of determining SCF wave functions for excited electronic states is examined for singlet states of two-electron systems using a Lowdin natural orbital transformation of the full CI wave function. This analysis facilitates the comparison of various SCF methods with one another. The distribution of the full CI states among the natural orbital MCSCF states is obtained for the S states of helium using a modest Gaussian basis set. For SCF methods that are not equivalent to the full CI wave functions, it is shown that the Hartree-Fock plus all single excitation wave functions are equivalent to that of Hartree-Fock plus one single excitation. It is further shown that these wave functions are equivalent to the perfect pair or TCSCF wave functions in which the CI expansion coefficients are restricted to have opposite signs. The case of the natural orbital MCSCF wave function for two orbitals is examined in greater detail. It is shown that the first excited state must always be found on the lower natural orbital MCSCF CI root, thus precluding the use of the Hylleras-Undeim-MacDonald (HUM) theorem in locating this state. It is finally demonstrated that the solution obtained by applying the HUM theorem (minimizing the upper MCSCF CI root with respect to orbital mixing parameters) is an artifact of the MCSCF method and does not correspond to any of the full CI states.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080424
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Strain energy minimization study of the mechanism of, and the barrier to, conformational interconversion in five-membered diamine chelate rings (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 651-657 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The method of Lagrangian multipliers is used to constrain torsion angles during molecular mechanics refinement for the purpose of plotting strain energy against a reaction coordinate. A complete two-dimensional analysis of the conformational interconversion from δ- to λ-[Co(ethane-1,2-diamine) (NH3)4]3+ reveals a mechanism in which the transition state geometry has an envelope conformation and an inversion barrier of 15.7 kJ mol-1. Substitution at the carbon atoms, variation of the metal-nitrogen distance, and replacement of the amine ligands with bidentate amines only slightly alters the inversion barrier. Substitution at the nitrogen atoms of the bidentate ligand increases the inversion barrier significantly to 24.6 kJ mol-1 for (N,N,N′,N′-tetramethylethane-1,2-diamine) [(NH3)4]3+.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080510
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    A specific inhibitor design approach by means of molecular dynamics calculation for porcine pancreatic elastase (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 645-650 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A 27-picosecond (ps) molecular dynamics calculation has been carried out for the 1:2 enzyme-ligand complex between porcine pancreatic elastase (PPE) and acetyl-alanine-proline-alanine (APA). A data analysis has been carried out using a total of 450 structures. During the simulation, the root-mean-square fluctuations (RMSF) increased compared with the x-ray data. Some differences of the hydrogen bond arrangement in the MD average structures are found especially for SER 195, suggesting the fluctuations of the ligand molecules. The radius of gyration decreased a little during the simulation. Although intermolecular hydrogen bonds between two substrates (APA1 and APA2) has not been found by a 1.65-Å high-resolution x-ray diffraction study, the MD calculation showed the intermolecular hydrogen bond between them to be 3.2 Å. The extended active site of PPE is so wide compared with the size of a tripeptide that such a hydrogen-bound hexapeptide can be more specific than tripeptides, which is consistent with the kinetic data previously reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080509
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Basis sets for molecular interactions. 2. Application to H3N—HF, H3N—HOH, H2O—HF, (NH3)2, and H3CH—OH2 (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 674-682 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Modifications of the standard 6-31G** basis set as recommended in the accompanying paper are found to markedly lower the basis set superposition error (BSSE) in the title complexes, in contrast to enlargement to a triple-ζ scheme or by addition of a diffuse sp shell or a second set of d-functions without prior optimization, all of which lead to BSSE increase. After appropriate correction for correlation and superposition effects, all basis sets (with the exception of the standard 6-31G** and 6-311G** with their very large BSSE) predict the cyclic geometry of NH3 dimer to be more stable than the linear arrangement. Correlation and BSSE can shift the equilibrium intermolecular distance in H3CH-OH2 by up to 0.4 Å. Failure to correct for superposition error leads to a drastic exaggeration of both the SCF and MP2 components of the interaction energy in this complex. Much better estimates are furnished by our recommended basis sets with their smaller superposition errors.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080513
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080601
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Bond critical points in the electronic structures of the main group diatomic hydrides of lithium through bromine (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 489-498 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The bond critical points and associated electronic properties of the diatomic hydrides of the twenty-one main group elements from lithium to bromine have been calculated with large basis sets. As part of a systematic study of the polarity of chemical bonds, the position of the bond critical point, the charge density at the bond critical point, the Laplacian of the charge density at the bond critical point, and the molecular dipole moment of each molecule have been calculated. Particular attention has been paid to the effect of bond length elongation and contraction on the electronic properties. Variation of the bond length reveals that with atoms of low electronegativity, the bond critical point of AH tends to follow atom A, whereas with atoms of high electronegativity, the bond critical point tends to follow the hydrogen atom as the bond lengthens. Furthermore, it is shown that some properties of the diatomic hydrides vary monotonically within each row of the periodic table, while others effect a classification according to the character of the bond.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080429
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Innate degree of freedom of a graph (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 516-521 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: For a Kekulé structure we consider the smallest number of placements of double bonds such that the full Kekulé structure on the given parent graph is fully determined. These numbers for each Kekulé structure of the parent graph sum to a novel structural invariant F, called the degree of freedom of the graph. Some qualitative characteristics are identified, and it is noted that apparently it behaves differently from a couple of other invariants related to Kekulé structures.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080432
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Computer enumeration and generation of physical trees (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 549-554 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A computer-oriented method for the enumeration and generation of physical trees is presented. Physical trees depict acyclic chemical structures, but the term physical is used to stress the process by which the structures are produced.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080435
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    Announcement (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 916-916 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080618
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Computer enumeration of polyhexes using the compact naming approach (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 906-915 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The enumeration of polyhexes can be easily carried out by utilizing a compact name (CN) approach to code chemical structures. The Fortran program performing generation of benzenoid hydrocarbons with 1-10 rings is presented. The computed structures are divided into various classes according to their cata- or peri- as well and non- or radicaloid character. Use of the additive nodal increments (ANI) approach leads to algorithm producing representative samples of the polyhexes' sets which can be applicable in testing of various topological formulae.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080617
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080701
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    On color polynomials of Fibonacci graphs (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 956-959 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A recursion exists among the coefficients of the color polynomials of some of the families of graphs considered in recent work of Balasubramanian and Ramaraj. Such families of graphs have been called Fibonacci graphs. Application to king patterns of lattices is given. The method described here applies only to the so called Fibonacci graphs.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080704
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    Fast matrix multiplication (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 960-964 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Several implementations of matrix multiplication (MMUL) in Fortran and VAX assembly language are discussed. On a VAX-11/780 computer, the most efficient MMUL is achieved through vector-scalar-multiply-and-add (VSMA) operations, rather than by means of dot products. We also discuss optimal MMUL algorithms for use in virtual memory machines when the data overflow the working set.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080705
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    Gaussian basis sets for the fifth row elements, Mo-Cd, and the sixth row elements W-RN (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 982-1003 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Gaussian basis sets, consisting of 17 s-type, 12 p-type, and 8 d-type functions, for the fifth row elements, Mo—Cd, and 19 s-type, 14 p-type (16 p-type), 10 d-type and 5 f-type functions for the sixth row elements, W—Rn, are presented. The basis sets are of double zeta quality, and are optimized to .002 a.u. in the energy. The energies are compared with D.Z. STO basis sets.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080708
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    An efficient newton-like method for molecular mechanics energy minimization of large molecules (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1016-1024 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Techniques from numerical analysis and crystallographic refinement have been combined to produce a variant of the Truncated Newton nonlinear optimization procedure. The new algorithm shows particular promise for potential energy minimization of large molecular systems. Usual implementations of Newton's method require storage space proportional to the number of atoms squared (i.e., O(N2)) and computer time of O(N3). Our suggested implementation of the Truncated Newton technique requires storage of less than O(N1.5) and CPU time of less than O(N2) for structures containing several hundred to a few thousand atoms. The algorithm exhibits quadratic convergence near the minimum and is also very tolerant of poor initial structures. A comparison with existing optimization procedures is detailed for cyclohexane, arachidonic acid, and the small protein crambin. In particular, a structure for crambin (662 atoms) has been refined to an RMS gradient of 3.6 × 10-6 kcal/mol/Å per atom on the MM2 potential energy surface. Several suggestions are made which may lead to further improvement of the new method.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080710
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    A powerful truncated Newton method for potential energy minimizationThis work would not have been possible without the expert contibutions of Charles Peskin and Suse Broyde. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1025-1039 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: With advances in computer architecture and software, Newton methods are becoming not only feasible for large-scale nonlinear optimization problems, but also reliable, fast and efficient. Truncated Newton methods, in particular, are emerging as a versatile subclass. In this article we present a truncated Newton algorithm specifically developed for potential energy minimization. The method is globally convergent with local quadratic convergence. Its key ingredients are: (1) approximation of the Newton direction far away from local minima, (2) solution of the Newton equation iteratively by the linear Conjugate Gradient method, and (3) preconditioning of the Newton equation by the analytic second-derivative components of the “local” chemical interactions: bond length, bond angle and torsional potentials. Relaxation of the required accuracy of the Newton search direction diverts the minimization search away from regions where the function is nonconvex and towards physically interesting regions. The preconditioning strategy significantly accelerates the iterative solution for the Newton search direction, and therefore reduces the computation time for each iteration. With algorithmic variations, the truncated Newton method can be formulated so that storage and computational requirements are comparable to those of the nonlinear Conjugate Gradient method. As the convergence rate of nonlinear Conjugate Gradient methods is linear and performance less predictable, the application of the truncated Newton code to potential energy functions is promising.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080711
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    Atomic charges derived from electrostatic potentials: A detailed study (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 894-905 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new algorithm for fitting atomic charges to molecular electrostatic potentials is presented. This method is non-iterative and rapid compared to previous work. Results from a variety of gaussian basis sets, including STO-3G, 3-21G and 6-31G*, are presented. Charges for a representative collection of molecules, comprising both first and second row atoms and anions are tabulated. The effects of using experimental and optimized geometries are explored. Charges derived from these fits are found to adequately reproduce SCF dipole moments. A small split valence representation, 3-21G, appears to yield consistently good results in a reasonable amount of time.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080616
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    On the use of constraints in molecular mechanics. II. The Lagrange multiplier method and non-full-matrix Newton-Raphson minimization (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1099-1103 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: It is shown how the Lagrange Multiplier method for constrained minimization can be implemented in a molecular mechanics program using the common approximations to the full-matrix Newton-Raphson minimization. The method reduces the number of cycles to achieve convergence, and also stabilizes the refinement process. Increases in computer memory requirements are small. As an application, the conformational surface of cycloheptane is calculated.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080805
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    An evaluation of the performance of diffuse function-augmented basis sets for second row elements, Na-ClPart IV of a series on Efficient Diffuse Function-Augmented Basis Sets for Anion Calculation. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1109-1116 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The energetic effects of the addition of diffuse functions to molecules with second-row elements are much less dramatic than those for their first-row counterparts. Although diffuse functions on second-row elements have little effect on the geometries and vibrational frequencies of neutral molecules, significant changes are found for anions. While the largest basis set, 6-31 + G*, generally performs best, the results at 3-21 + G* are comparable, and this basis can be recommended for practical applications.
    Additional Material: 10 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080807
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    Benzene-benzene (phenyl-phenyl) interactions in MM2/MMP2 molecular mechanics calculations (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1139-1145 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The MM2/MMP2 force-field gives an incorrect description of benzene-benzene interactions. This deficiency may be overcome by the addition of electrostatic interactions. Using point charges of -0.15 on carbon and +0.15 on hydrogen, a good agreement between benzene dimer potentials calculated by MMP2 and ab initio SCF CI potentials is obtained. The influence of the addition of point charges on calculated structures and conformational energies has been studied. Examples are given in which the addition of electrostatic interactions between phenyl groups substantially improves calculated conformational energies.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080811
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    MNDO Calculations on [n]metacyclophanes (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1154-1169 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: MNDO calculations on [n]metacyclophanes and a variety of related compounds are reported. An analysis of the strain, imposed by the oligomethylene bridge, and its distribution over the distorted benzene ring and the oligomethylene bridge is presented. The effect of strain and bending of the benzene ring on aromatic delocalization is investigated by a comparison of ΔHof of the bent benzene systems with that of a correspondingly bent, but localized 1,3,5-cyclohexatriene. The results indicate that, even in the case of the highly bent [4]metacyclophane (1a), localization is unfavorable by about 10 kcal/mol.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080813
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    Announcement (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1232-1232 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080819
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    On the importance of size-consistency corrections in semiempirical MNDOC calculations (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 48-50 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Energies obtained by configuration interaction calculations including all double excitations with regard to the Hartree-Fock reference determinant can empirically be corrected to size consistency using either the Langhoff-Davidson (LD) formula or a formula suggested by Pople, Seeger, and Krishnan (PSK). Semiempirical MNDOC calculations suggest that for molecular systems with a large number of electrons and important correlation effects the PSK correction is superior to the LD correction.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    Polarization counterpoise corrections to correlated hydrogen bond interaction energies (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 81-83 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Basis set superposition error in hydrogen-bonded systems can exaggerate attraction calculated from self-consistent field energies as well as from electron correlation energies. One cause of this error is the basis set deficiency in describing the charge polarization of one constituent molecule when its bonding partner approaches. That constituent molecule's description is improved partly because of the proximity of the partner's basis functions, independent of real attraction. That polarization-related error is shown to occur primarily at the SCF level and not at correlated levels.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Hydration structures and energetics of phospholipid (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 57-66 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Using previously reported ab initio potentials of the intermolecular interaction energies of phospholipid (PL), Lysophosphatidyl Ethanolamine, with one Na+ ion and one water molecule, we performed Monte Carlo simulations for PL-water and PL-Na+-water systems. Water-water and PL-water interaction energetics of PL hydration sites are analyzed to understand, in a qualitative way, why the PL head part shows hydrophilicity and the tail part shows hydrophobicity. The interaction of Na+ with PL, as well as the interaction of water with PL, is visualized from the analysis of the hydration structures near PL, and the radial distribution functions are analyzed for selected hydration sites. The PL molecule shows much stronger interaction with Na+ than with water. The Na+ ion is likely to be strongly bound to PO4-, even to the extent of being trapped, whereas, for water, there exist two strong binding regions near NH3+ and PO4-. Three water molecules near NH3+ are much more strongly bound than four water molecules near the double-bonded oxygens of PO4-. The hydrogens of CH2 adjacent to NH3+ show somewhat strong hydrophilicity, while the hydrogens of CH2 adjacent to PO4- does not show such characteristics. The CH2 groups at the PL tail part give repulsive interactions with water molecules, showing hydrophobicity. Water molecules near the PL tail are stabilized only by water-water interactions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Ab initio calculations on the effect of polarization functions on disiloxane (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 84-93 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The effect of polarization functions for ab initio molecular orbital calculations at the 3-21G* level has been studied for disiloxane. Calculated molecular geometry, dipole moment, and the linearization barrier variation were analyzed for different uncontracted polarization functions. It was concluded that variation of the polarization function on oxygen has only a minor influence on the molecular properties of disiloxane, but its presence is required to obtain a bent geometry for the disiloxane bond. The calculated molecular properties of disiloxane are greatly influenced when the polarization function on silicon is varied. Two different values (0.3 and 0.9) for the exponent of the silicon polarization function provide results comparable to the experimental values for disiloxane. The only significant differences between the results obtained from ab initio calculations using the two polarization functions are in net atomic charges. The uncontracted polarization function of silicon with a value of 0.3 for its exponent is transferable to other organosilicon compounds. Calculated molecular geometries of flexible or rigid structures are in very good agreement with the experimental values.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080111
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    Reliable Gaussian basis sets for closed-shell atoms (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 117-131 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Medium size Gaussian basis sets for inert-gas atoms (from neon to xenon) have been constructed using the energy optimization method which maintains reliable description of the long-range valence atomic region. These basis sets have been tested in SCF calculations on homonuclear inert-gas dimers. For Ne2, Ar2, and Kr2, the present results have been analyzed carefully and compared with those obtained using extended basis sets (for Kr2 extended benchmark calculations are also reported). Our interation energies agree well with accurate values and are compared with experimental data. For Ne2 and Ar2, detailed studies of basis set superposition error also are presented.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Comparison of the use of the MNDO and MINDO/3 methods with ab initio methods to study tautomerism in histamine, 2- and 4-methylhistamine (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 142-148 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The semiempirical MNDO and MINDO/3 methods are used to study the various tautomeric forms of histamine, 2-methylhistamine, and 4-methylhistamine. Comparisons of the optimized structures and tautomerization energies are made with values obtained from ab initio Hartree-Fock calculations using the 3-21G and STO-3G basis sets. Based on these results and previous comparisons of STO-3G results with x-ray structures, the present results indicate that while there are some differences in the values of the structural parameters, the changes in structure upon tautomerization and/or protonation are very similar. Further analysis of the MNDO and MINDO/3 structures by means of their utilization in 3-21G and STO-3G calculations indicates that either of these semiempirical methods provides reliable values for the structural parameters. Both methods give good qualitative agreement with the ab initio calculations for the relative energies of the various tautomers in the three compounds. In these studies the MNDO method appears to give better quantitative agreement with the 3-21G and STO-3G results than the MINDO/3 method.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080206
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Macromolecular structure and specificity: Computer-assisted modeling and applications, Edited by Babu Venkataraghavan and Richard J. Feldmann, Annals of the New York Academy of Sciences, New York, 209 pp. Price: $48.00 (1985). (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 185-185 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080211
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080401
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    Converged calculations of rotational energy transfer in HF—HF collisions (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 282-290 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We have performed large-scale close coupling calculations of rotational-to-rotational energy transfer in HF—HF collisions for the realistic potential energy surface of Brobjer and Murrell. We employ up to 525 angular terms in the expansion of the potential and up to 440 coupled channels in the rotational-orbital basis set. The results for zero total angular momentum are well converged for relative translational energies up to over 0.6 eV, and they show extensive rotational excitation.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080403
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Announcement (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 186-186 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080212
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Time step error in diffusion Monte Carlo simulations: An empirical study (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 412-419 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Diffusion Monte Carlo (DMC) is a random walk computational method for solving the ground-state Schrödinger equation for atoms or molecules. One obtains a biased simulated energy which is used to estimate the exact energy, where the bias increases with the time step used in the simulation. We present six new DMC algorithms, all of which have the same theoretical justification. Yet, when applied to the LiH and H2 molecules, the algorithms give results with markedly different error. Furthermore, algorithms which exhibit a small error when applied to one molecule show significantly greater error for the other. The explanation for these results relates to sampling of configuration space in the neighborhood of the nuclei. We investigate this issue hoping that our results will aid in the design of more efficient DMC algorithms.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080418
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Chemical applications of topology and group theory. 23. A comparison of graph-theoretical and extended Hückel methods for study of bonding in octahedral and icosahedral boranesPaper presented at the CIC Symposium on Computational and Mathematical Chemistry, Saskatoon, Saskatchewan, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 341-349 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The graph-theory derived model for the bonding topology in the globally delocalized polyhedral boranes B6H62- and B12H122- is evaluated by comparison of the energies of the core molecular orbitals with those obtained by the 1962 LCAO-MO extended Hückel calculations of Hoffmann and Lipscomb. Of particular interest is how well the complete graphs K6 and K12 used in the graph-theory derived model approximate the bonding topologies of the unique internal orbitals (radial orbitals) of the octahedron and icosahedron, respectively. In the case of the B6H62- octahedron the single positive eigenvalue of the K6 graph corresponds to the results from the extended Hückel calculations. In addition, the parameters from the latter calculations indicate a ratio of 0.625 for the overlap of the unique internal orbitals of the trans atom pairs relative to cis atom pairs as compared with unity implied by an unweighted K6 graph. In the case of the B12H122- icosahedron the graph-theory derived model is far less satisfactory since the single positive eigenvalue of the K12 graph disagrees with the four bonding core molecular orbitals (an A1g and three triply degenerate T1u molecular orbitals) found by the extended Hückel calculations after removing the effect of the mixing of core and surface bonding orbitals corresponding to the same irreducible representations. However, this core-surface orbital mixing raises the energy of the triply degenerate T1u core molecular orbitals to antibonding levels so that the graph-theory derived model fortuitiously gives correct skeletal electron counts for the regular icosahedron despite this fundamental error.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080410
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    PERTURB: A special-purpose algebraic manipulation program for classical perturbation theory (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 397-411 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Classical perturbation theory provides a particularly promising route to EBK quantization of nonseparable systems. However, the number of terms generated when implementing perturbation theory for systems with more than two degrees of freedom can prove too large for general purpose symbolic manipulators to handle. We describe PERTURB, a specialized algebraic manipulation program written in C for quantization of multidimensional systems. A review of operator based classical perturbation theory is given, and the relationship between this type of perturbation theory and quantum mechanical Van Vleck perturbation theory discussed. The relative performance of the Dragt-Finn and Lie transform algorithms is assessed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080417
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Quasiperiodization in classical hyperchaos (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 510-515 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A 1D gas with maximal chaos in the sense of Sinai is considered. An idea originally proposed by Gibbs (that particle indistinguishability imposes a well-defined symmetry having nontrivial quantitative implications) is investigated in the light of this example. A new quantitative implication of the Gibbs paradox, quasiperiodization, is found to apply to the present system.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080431
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Graph generators (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 522-535 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We consider the construction of highly symmetrical vertex transitive graphs. Some such graphs represent the degenerate rearrangements in which a molecule or an ion is formed by breaking and making bonds so that the final and the initial skeleton is identical. The approach is closely related to Cayley's graphs for selected groups. We restrict the choice of generators to symmetric matrices. Successive multiplications of such matrices generate other permutation matrices of the same dimension, each new matrix representing a new vertex for a transitive graph under the construction. In particular we restrict our discussion to matrices of dimension 3 and 4 and proceed to construct systematically all transitive graphs using 4 × 4 symmetric matrices as generators.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080433
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Column design. 3. Theoretical studies of a chiral stationary phase used in column chromatography (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 753-760 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Conformational features of a chiral stationary phase used in column chromatography are discussed. The syn forms invoked in chiral recognition models are consistent with MNDO and MM2 calculations. It is speculated that the inherent flexibility of the syn form makes these phases effective templates for analyte binding.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080602
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    Hamiltonian dynamics of chemical reactions. Consecutive first-order reactions and reactions possessing one autocatalytic intermediatePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 744-751 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A recently proposed Hamiltonian approach to phenomenological chemical kinetics [T. Georgian and G.L. Findley, Int. J. Quantum Chem., Quantum Biol. Symp. 10, 331 (1983); T. Georgian, J.M. Halpin, and G.L. Findley, Int. J. Quantum Chem., Quantum Biol. Symp. 11, 347 (1984)] is applied to all consecutive first-order, single-step reactions, and to all reactions possessing one autocatalytic intermediate. The reaction Hamiltonians presented are shown to be consistent with the phenomenological rate equations and the relationship between reaction form and the form of the reaction potential is discussed. In particular, we show: (1) that the interaction between consecutive reactions manifests itself as a coupling term in the reaction potential, a term which may be eliminated via transition to “normal reaction coordinates” for the chemical system; and (2) that coupled sets of autocatalytic reactions give rise to coupling terms in the reaction Hamiltonian which are characteristic of the reaction mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080519
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    Electrostatic interaction of a solute with a continuum. Improved description of the cavity and of the surface cavity bound charge distribution. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 778-787 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Algorithms for a finer description of cavities in continuous media and for a more efficient selection of sampling points on the cavity surface are described. Applications to the evaluation of solute surface and volume and to the calculation of the solute-solvent electrostatic interaction energy, as well as of the cavitation energy are shown as examples.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080605
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulation of the 1:1 enzyme-ligand complex between porcine pancreatic elastase and acetyl-alanine-proline-alanine (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 801-809 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A 31.5 picosecond (ps) MD calculation has been completed for the 1:1 enzyme-ligand complex between porcine pancreatic elastase (PPE) and acetyl-alanine-proline-alanine (APA). The 1:2 complex studied crystallographically at product saturation conditions precludes the study of a 1:1 complex (PPE and APA1); this objective has been achieved by computational methods described here. The acetyl group of the ligand was found to occupy two neighboring sites, one within the primary specificity site and the other out into solution. The primary change of the ligand structure is ψ1 torsion angle being 171.5°. Supported by an interactive graphic display, the dynamical fluctuations of a smaller ligand compared with the width of the active site as PPE were observed by the MD simulation, although the complex has not been detected by any spectroscopic method.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080608
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Towards a valence-orbital/bond-orbital description of biochemical H-bonds from ab initio calculationsWork partially presented at the International Symposium on Applications of Mathematical Concepts to Chemistry, Dubrovnik, Yugoslavia, September 2-5, 1985. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 816-825 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We have studied the system NH3…H+…HN=CH-CH=CH2, which is a model for an enzymatic site characterized by an important pi-electron contribution, with the aim of contributing to the molecular orbital theory of H-bridge formation and proton transfer. Ab initio canonical orbitals from STO-3G and 4.31G bases have been determined for various geometrical configurations, and analyzed in terms of Mulliken's Modified Valence Atomic Orbitals obtained by suitable contraction. Also, the orbital correlation diagram has been obtained and discussed. At least two sigma MO's can be considered specific of the H-bond: they involve the expected hybrids giving rise to stereoelectronic effects associated with the lone pairs of the two heavy atoms. Population analysis suggests that the bridge hydrogen changes its population very little during its motion along the bridge, although its in situ atomic orbital does not change: this means that it acts essentially as a relay center in charge transfer between the two moieties of the H-bonded complex. As expected on intuitive grounds, charge transfer involves essentially the sigma cores.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080610
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Molecular orbital theory of the properties of inorganic and organometallic compounds. 6. Extended basis sets for second-row transition metals (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 880-893 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A series of efficient split-valence basis sets for second-row transitions metals, termed 3-21G, has been constructed based on previously formulated minimal expansions of Huzinaga, and in a manner analogous to the previous development of 3-21G basis sets for first-row metals. The Huzinaga three Gaussian expansions for s- and p-type orbitals of given n quantum number have been fit by least squares to new three Gaussian combinations in which the two sets of functions share the same Gaussian exponents. The original three Gaussian expansions for 1s, 3d, and 4d atomic orbitals have been employed as is. The valence description comprises 4d- 5s- and 5p-type functions, each of which has been split into two and one Gaussian parts. 5p functions, while not populated in the ground state of the free atom, are believed to be important in the description of the bonding in molecules.The performance of the 3-21G basis sets is examined with regard to the calculation of equilibrium geometries and normal-mode vibrational frequencies for a variety of simple inorganic and organometallic compounds incorporating second-row transition metals.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080615
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    Recent advances in multireference second order perturbation CI: The CIPSI method revisited (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 39-47 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The evolution of the CIPSI method, with the latest modifications recently implemented in our laboratory, is described. A new version, based on a diagrammatic technique, is presented. Test calculations which have been run on water, ethylene, and transacrolein, show that the new method is a powerful tool for the study of medium-size molecular systems.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    The role of d functions in ab initio calculations. II. The deformation densities of SO2, NO2, and their ions (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 6-27 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Comparison of the optimized geometries and SCF energies for the series XO2+, XO2, XO2-, XO2-, with X = S,N shows that d(S) functions cause larger bond shortening and energy drop than d functions centered on first-row atoms. This is further emphasized on comparing the separate effects of d(central atom) and d(O) functions for SO2 and NO2-, which are similar only for the first-row molecule. The d(S) functions are also essential for proper prediction of the OSO angles. The deformation densities calculated for each series and the corresponding X-O shared populations, change as expected on adding electrons first into σ* then into π* molecular orbitals. In the regions around nuclei the deformation densities express the behavior of the atomic s and p valence orbitals or of their product inside their radial nodes. Introduction of d functions causes substantial polarization effects. For X = N these are mostly local except in the bonding regions where d(N) and d(O) functions are somewhat interchangeable. However, d(S) functions induce also unique changes in the deformation density near O. They cause π and π′ charge migration from O to S and a σ flow in the opposite direction. These effects are largest for the hypervalent species. The unique populations of the d(S) functions are much larger than those of d(N) and d(O) functions. The contribution of d(S) functions to bonding is related to the larger amplitude at small radii of the atomic 3d(S) orbital as compared with that of 3d(N). The difference in amplitudes is related to penetration effects. Diffuse p functions affect geometries and SCF energies of doubly, but not singly negative ions. However, they mostly describe the diffuse nonbonding clouds and do not affect bonding patterns.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080103
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080201
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Character tables and symmetry eigenvectors for two C3v rotor molecular systems (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 380-388 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The character tables of the Altmann groups for the double internal rotation of C3v rotor molecules of different symmetries were determined. These symmetries were those of para-xylene, trans-1,2-dimethylcyclopropane, cis-N-methylethylidenimine, dimethylamine, and a dimethylated asymmetrical molecule. From these character tables, the symmetry eigenvectors, which block diagonalize the Hamiltonian matrix, were deduced. The symmetry eigenvectors were derived with the help of a small computer.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080415
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    Introduction (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 281-281 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080402
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Transition structure in a diabatic surface formalism (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 296-306 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The theory of an implementation of the diabatic surface model within the Heitler-London valence bond approach is described. It is shown that the HL-VB wave function can be obtained from a Van-Vleck transformation of an MC-SCF wave function which has been built from atom-localized orbitals. This wave function is built from a superposition of two diabatic components, reactantlike and productlike. The transition structure is then obtained as the minimum of the seam of intersection of the diabatic surfaces and the algorithm for performing this constrained optimization is described. Several areas of application are also discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080405
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Coupled equations approach to multiphoton molecular processes (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 313-323 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Using the dressed molecule picture of molecule radiation interactions (A.D. Bandrauk et al., J. Chem. Phys., 79, 3256; 80, 4926; 83, 2840) one can deduce multiphoton processes (absorption, scattering, nonlinear optical properties, etc.) amplitudes from coupled second-order differential equations with electronic surfaces and transition moments as input data obtainable from quantum chemical calculations. The present approach enables one to include in the calculation bound and continuum states simultaneously by the use of appropriate boundary conditions for the numerical solutions of these coupled equations. In the case of weak radiative couplings, one recovers the usual Fermi-Golden rule expressions for electronic absorption, raman scattering, etc. The method is thus quite general, bridging the weak field (traditional photochemistry) and the strong field (laser chemistry) regimes which are attainable with today's lasers. The numerical solutions of the coupled equations give us the stationary states of the molecule + radiation system, called dressed molecule. Preparation of the initial state can be mimicked in the coupled equations by an artificial channel method for processes involving a final-state dissociation. Examples of such calculations will be presented in the diatomic Cl2 for which several ab initio electronic states and transition moments were available.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080407
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    An algorithm for geometry optimization without analytical gradients (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 563-574 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A numerical algorithm for locating both minima and transition states designed for use in the ab initio program package GAUSSIAN 82 is presented. It is based on the RFO method of Simons and coworkers and is effectively the numerical version of an analytical algorithm (OPT = EF) previously published in this journal. The algorithm is designed to make maximum use of external second derivative information obtained from prior optimizations at lower levels of theory. It can be used with any wave function for which an energy can be calculated and is about two to three times faster than the default DFP algorithm (OPT = FP) supplied with GAUSSIAN 82.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080502
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Analysis of the π-electronic structure of infinitely large networks. I. Some remarks on the characteristic polynomial and density of states of large polycyclic aromatic hydrocarbons (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 358-366 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: General expressions of the characteristic polynomials of various series of cyclic and linear polymers of polycyclic aromatic hydrocarbons are presented, i.e., polyacene, zigzag-polyacene, 1,4-dimethylbenzene polymer, polyperylene, etc. The densities of states of cyclic and linear polymers with the same repetitive units are shown. In some cases the allowed region of the energy levels of these polymers is found not to be the same. Several related problems are discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080412
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Linear notations and molecular graph similarity (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 367-374 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Two simple linear notation systems are suggested to encode molecular structure including stereochemical elements. Both systems give rise to a unique numbering of the molecular graph, and thus also lead to a unique linear notation. Both linear notation systems are extremely compact and require only standard chemical symbols. A string comparison technique is developed to measure the similarity of two molecular linear notations. This procedure allows one to define a molecular similarity index with values that range from zero to unity, the zero value characterizing complete dissimilarity and the value of unity denoting identity. The notation and similarity index procedures are applied to several small molecular structures.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080413
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Generalized potential surfaces under inclusion of nuclear motion (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 350-357 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new method for the solution of the vibronic Schrödinger equation is presented. The proposed approach allows the preservation of the concept of potential surfaces under inclusion of nuclear motion. The dynamical interaction of electrons and nuclei is partially included in the equation determining the potential surfaces. The corresponding electronic wave functions can be used as a basis for a generalized representation. Since the variation principle is involved for the determination of the potential surfaces, the proposed representation may be considered as a generalization of the adiabatic one. As a consequence the vibrational wave equation and the calculation of radiationless transition probabilities is simplified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080411
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    The density amplitude ρ½ and the potential which generates it (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 375-379 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The square root of the density ρ½ satisfies a Schrödinger equation with an effective local potential V(r). The form of this potential is obtained for (a) the ground state of the Be atom, (b) neutral atoms in the limit of very large atomic number from the statistical theory, and (c) almost spherical molecules XH4, again in the limit of many electrons. Some comments are made on the possibility of relativistic generalization of this method.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080414
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Computational studies of 1,2-dithiete and dithioglyoxal (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 389-396 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio calculations are reported on the energies, geometries, vibrational frequencies, and ionization potentials of the H2C2S2 isomers: 1,2-dithiete, cis-dithioglyoxal, and trans-dithioglyoxal. In contrast to most earlier computations, the results of this work indicate that 1,2-dithiete and cis-dithioglyoxal lie close in energy (within 3 kcal/mol) with the dithial more stable. Trans-dithioglyoxal is found to be 4.1 kcal/mol more stable than the cis isomer and faces a barrier to internal rotation of 5.5 kcal/mol. The predicted rotational constants for 1,2-dithiete agree within ∼0.05 GHz with the experimentally observed values thus lending credence to the predictions for cis-dithioglyoxal (Ae 14.30683, Be 2.46324, Ce 2.10143 GHz). Vibrational frequencies are given as potential aids to the identification of these molecules. 6-31G* ΔSCF calculations predict that at low energies (8 to 13 eV) the photoelectron spectra of 1,2-dithiete, cis-dithioglyoxal and trans-dithioglyoxal should be similar.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080416
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Discrete models of growth and dynamical percolation in chemistry (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 428-435 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Space-time lattice (cellular automaton) models of pattern formation and growth are described. Suitable local rules for automation evolution represent the spreading of wave fronts of activity in an excitable medium. A random distribution of seeds produces expanding rings that fuse and are annihilated. The seeding density, pA, is used as a scaling parameter to give unique, reduced dynamics in an arbitrary dimension d. For d = 2, in this (continuum) picture, the rings fuse globally (percolate) at a critical instant, t̂c = 0.45. For the unscaled time evolution, dynamical percolation is examined in the pA × t plane. A swath of these percolating states is found. On the “explosion” boundary of this swath the percolation cluster just forms; on the “implosion” boundary it breaks up. Using a small-sample method the fractal dimension of the critical (boundary) cluster is estimated to be 1.9 (±0.01). Also percolation for continuously emitting seeds, which produce “discs” of activity, is related to ring evolution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080420
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Algorithm for rapid calculation of Hessian of conformational energy function of proteins by supercomputer (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 625-635 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An improved algorithm is presented for rapid calculation of the hessian matrix for the conformational energy of a protein as a function of only dihedral angles. The speed of the calculation, which is about one order faster than by the previous method, is achieved by two considerations. First, the algorithm is designed to take advantage of the supercomputer pipeline architecture. Second, long-range, nonbonded interactions are cut off and long-range electrostatic interactions are approximated by dipole-dipole interactions in order to reduce the number of pairwise interactions that have to be computed. The results of benchmark tests of the program are given as applied for four globular proteins of different sizes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080507
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Molecular valence calculations on cyclohexasulfur, cycloheptasulfur, and cyclooctasulfur (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 658-662 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A theoretical study of homocyclic sulfur species S6, S7, and S8 was carried out using a molecular valence method involving stepwise approximations for orthogonality and core-valence interactions. The valence shell orbitals are described at the minimal basis level. The geometries of the molecules are predicted well as compared with other theoretical studies and the experimental values. The slight overestimation of the SS bond length is typical to the nonpolarized basis sets. The energies of the valence orbitals are well in accord with the conventional all-electron ab initio results. The trend in the stabilities of the three molecules is discussed. The present method provides an attractive possibility to study homocyclic and heterocyclic systems involving heavier chalcogens with no increase of the computing time.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080511
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Two approaches to the calculation of molecular resonance states: Solution of scattering equations and matrix diagonalizationPresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 683-699 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We have analyzed two approaches to reproduce the resonance expansion of the scattering matrix appropriate for the calculation of molecular resonance states. The first is based on the resonance theory of Siegert-Humblet-Rosenfeld (SHR) and the second on the Fano-Feshbach formalism. The direct method of calculating the resonance expansion characteristics, devised on the basis of the SHR theory, makes it possible to obtain the energies and partial widths (detailed decay rate constants) of resonances. The Fano-Feshbach formalism, on the other hand, elucidates the resonance state as a concept and facilitates the interpretation of calculation results. The use of computational methods is illustrated by the study of the decay of a model triatomic system and of gas-phase nucleophilic substitution reactions. Used in the latter case is the division of all degrees of freedom of the reacting system into the adiabatic and dynamic ones along with an algorithm of inclusion of the restricted dynamical treatment in the calculation of reaction rate constants.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080514
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Hartree Fock instabilities of sulfur-nitrogen ring systems: S2N2Presented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986 (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 727-735 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The Hartree-Fock instablities of S2N2 are reported and compared with those of S3N3- and S4N42+. These unsaturated sulfur nitrogen planar rings are π electron rich and although the symmetry adapted HF solutions are singlet stable at the experimental bond lengths they become unstable with only a very modest increase in bond length. The broken symmetry solutions for S2N3, S3N3-, and S4N42+ are of planar C2v type with one of the nitrogens stripped of its π electrons, producing a π hole.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080517
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Towards a quantum chemical software package utilizing transferable fragments as molecular building blocks (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 555-561 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Computer programs have been developed or are under development for the IBM personal computer that enable their users to get information on atomic charges, electrostatic potentials, conformational and other properties of molecular systems containing H, C, N, O, F, Si, P, S, or Cl atoms. The zero-order wavefunction is constructed of strictly localized molecular orbitals with fixed atomic orbital coefficients. The wave function can be refined by optimizing these coefficients, i.e., considering inductive effects via a coupled set of 2 × 2 secular equations within the CNDO/2 approximation. Delocalization and exchange effects are accounted for by expanding the wavefunction on a basis of the aforementioned strictly localized orbitals, instead of conventional atomic orbitals, and solving the corresponding SCF equations. Our method has been applied to the study of large systems. We calculated the electrostatic field of the complex of β-trypsin and basic pancreatic trypsin inhibitor and it has been found that strong field regions more or less coincide with hydration sites. A further potential application of protein electrostatic fields is in NMR spectroscopy. We found a linear correlation between CαH or backbone NH proton chemical shifts and the protein field at the site of the corresponding proton. At last, we propose a simple method to mimic the bulk around atomic clusters modeling crystalline and amorphous silicon. Based on this method we found a linear correlation between atomic net charges and bond angle distortions in silicon clusters with 35 atoms.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080436
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    An objective computer-oriented method for the calculation of formation constants from the formation function. A weighted least-squares curve fitting (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 575-580 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A computer program has been developed that calculates, using the weighted least-squares technique, the overall formation constants, Bi, of mononuclear complexes, the standard deviations of Bi, SDVi, and an estimate of goodness of fit, Goodness-of-Fit Parameter (GOFP), given a set of average ligand numbers, VNj, the corresponding free ligand concentrations, VAj, and an error parameter P. The formation function used is ∑(VNj - i) · (Bi) · (VAj)i = 0 where i ranges from O to n with a maximum of 10 and j ranges from O to l with a maximum of 40. The Bi and (Bi - SDVi) must be positive and GOFP must be either unity or as close to unity as possible. An option is available that allows the computation of P, if it is not provided, so that GOFP is equal or very close to unity. The method has been applied to the formation of the complexes Cadmium-Imidazole, Cobalt(II)-Bis(2-Quinaldylphenyl Ketone), Copper-Ammonia, Silver-4-Aminobutan-1-ol Nitrate, and Copper(II)-Bis(2-Quinaldylphenyl Ketone). The results are quite satisfactory and reliable as compared with other computational techniques. Input data and results for the five complexes mentioned are shown.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080503
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Strategies for vectorizing the sparse matrix vector product on the CRAY XMP, CRAY 2, and CYBER 205 (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 636-644 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Large randomly sparse matrix vector products are important in a number of applications in computational chemistry, such as matrix diagonalization and the solution of simultaneous equations. Vectorization of this process is considered for the CRAY XMP, CRAY 2, and CYBER 205, using a matrix of dimension of 20 000 with from 1% to 6% nonzeros. Efficient SCATTER/GATHER capabilities add coding flexibility and yield significant improvements in performance. For the CYBER 205, it is shown that minor changes in the IO can reduce the CPU time by a factor of 50. Similar changes in the CRAY codes make a far smaller improvement.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080508
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Basis sets for molecular interactions. 1. Construction and tests on (HF)2 and (H2O)2 (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 663-673 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Basis set superposition error (BSSE) remains one of the major difficulties besetting current ab initio calculations of molecular interactions. Despite the widespread notion that lowering of the BSSE to negligible magnitude requires extremely large basis sets, we show that simple modifications of basis sets of only moderate size (e.g., 6-31G**) can accomplish the same end at much reduced computational expense. These modifications include reoptimization of the orbital exponents within the framework of the relevant molecules, plus addition of a single diffuse shell of sp orbitals on nonhydrogen centers. Subsequent addition of a second set of d-functions further lowers the SCF BSSE, bringing it below 0.1 kcal/mol for both (HF)2 and (H2O)2. It is notable that addition of the latter d-functions without prior reoptimization of the valence orbitals produces the opposite effect of an increase in the BSSE. Although the MP2 BSSE is also substantially decreased by the above modifications, it appears difficult to reduce this quantity below about 0.4 kcal/mol.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080512
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    The inverse problem of isomer enumerationPresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 700-717 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The present article addresses the problem of identifying the structure of a parent compound through its chemical fingerprints such as the various numbers of isomeric substitution patterns, along the lines of Kekulé when he arrived at his benzene formula. In a pioneering paper (1929), Lunn and Senior laid out the conceptual framework for the permutation group description of substitution isomerism. It remained, however, for Pólya's celebrated contribution (1937) to initiate the actual mathematical realization of their vision. Pólya supplied the tools for solving the isomer enumeration problem: given a (symmetrical) parent compound, enumerate its spectrum of substitution patterns. The converse problem, though ranked the more interesting one by Lunn & Senior, hardly received any mathematical attention. The present article offers a complete and effective solution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080515
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    Molecular graphs as topological objects in spacePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 718-726 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Stereochemistry deals primarily with distinctions based on rigid geometry, e.g., bond angles and lengths. But some chemical species have molecular graphs (such as knots, catenanes, and nonplanar graphs K5 and K3.3) that reside in space in a topologically nontrivial way. For such molecules there is hope of using topological methods to gain chemical information. Viewing a molecular graph as a topological object in space makes it unrealistically flexible; but if one proves that a certain graph is “topologically chiral” or that two graphs are “topological diastereomers,” then one has ruled out interconversion under any physical conditions for which the molecular graph still makes sense. In this paper, we consider several kinds of topological questions one might ask about graphs in space, methology and results available, and specific topological properties of various molecules.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080516
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Ab-initioMRD-CI calculations on a C—NO2 decomposition pathway of nitrobenzenePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 736-743 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: To study molecular decomposition pathways it is necessary to use ab initio multireference determinant-configuration interaction or MCSCF (multiconfiguration SCF) calculations. The MRD-CI (multireference double excitation-configuration interaction technique of Buenker and Peyerimhoff) calculations on the decomposition pathway of nitrobenzene were carried out using all of the occupied molecular orbitals in the region of the bond being dissociated, plus all of the virtual orbitals. An effective CI Hamiltonian was used into which were folded the effects of all of the occupied molecular orbitals from which excitations were not allowed. So far we have investigated the lowest 1A1, 3A1, 1A2, 3A2, 1B1, 3B1, 1B2, 3B2 states and are investigating the higher states. Our results show a wealth of structure in the potential energy surfaces for the various electronic states of nitrobenzene as a function of distance. A number of the states are predissociative and change dominant configuration one or more times along these potential energy surfaces.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080518
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    CNDO Force constants for glucose (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 772-777 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Force constants for both anomers of glucose are evaluated using CNDO/Force method.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080604
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    A study of basis set effects on structures and electronic structures of phosphine oxide and fluorophosphine oxide (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 788-793 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A variety of basis sets have been used for geometric and electronic structure studies. Electronic effects were measured using integrated spatial electron populations (ISEP). The two largest basis sets used, 6-31G* and DZ+P, give significantly different results. Use of two d-orbital sets (6-31G*[dd]) or decontraction of the 2sp shell on phosphorus has little further effect. d-Orbitals on oxygen are required for consistent electronic structure results, and d-orbitals on fluorine have a small but significant effect. Use of diffuse functions, required for anions, is not recommended with small basis sets on neutral molecules. Large negative charges (≈-1.5) on oxygen are given by all of the larger basis sets by the ISEP procedure and indicate that the PO bond in these compounds is largely semi-polar. The best simple symbolic representation of phosphine oxide is H3P+—0-, rather than H3P=0.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080606
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Basis set and correlation effects on computed positive ion hydrogen bond energies of the complexes AHn · AHn + 1+1: AHn = NH3, OH2, and FH (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 810-815 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Basis set expansion and correlation effects on computed hydrogen bond energies of the positive ion complexes AHn · AHn + 1+1, for AHn = NH3, OH2 and FH, have been evaluated. The addition of diffuse functions on nonhydrogen atoms is the single most important enhancement of split-valence plus polarization basis sets for computing hydrogen bond energies. Basis set enhancement effects appear to be additive in these systems. The correlation energy contribution to the stabilization energies of these complexes is significant, with the second order term being the largest term and having a stabilizing effect. The third order term is smaller and of opposite sign, while the fourth order term is smaller yet and stabilizing. As a result, computed MP4 stabilization energies are bracketed by the MP2 and MP3 energies. The overall effect of basis set enhancement is to decrease hydrogen bond energies, whereas the addition of electron correlation increases stabilization energies.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080609
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    A force field for allenes and for nonlinear acetylenes within the MM2 approximation (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1225-1231 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Geometries and heats of formation for allenes may now be calculated with an extended version of MM2. The torsional barriers about bonds in an acetylenic unit are much more complicated than originally thought, if the unit is nonlinear. Ab initio calculations have been used to show just what these torsional barriers are, and the MM2 force field has been adapted to this information.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080818
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Refined ab initio 6-31G split-valence basis set optimization of the molecular structures of biphenyl in twisted, planar, and perpendicular conformations (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1057-1065 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Improved full ab initio optimizations of the molecular structure of biphenyl in twisted minimum energy, coplanar, and perpendicular conformations by use of Poles's GAUSSIAN 82 program have been performed in the 6-31G basis set. These lead to geometries and energies of much higher reliability than our earlier STO-3G results. The torsional angle Φmin obtained now is 45.41° in close agreement with the recent experimental value of 44.4° ± 1.2°. Calculated CC distances may be converted to experimental ED rg-values by means of independently determined linear regression correlations with very high statistical confidence, although they agree better with experimental x ray data for coplanar biphenyl without this correction. Calculated intramolecular angles are very similar for both STO-3G and 6-31G basis sets. The calculated torsional energy barrier towards Φ = 90° (ΔE90) is 6.76 kJ/mol in close agreement with the experimental-31G value of 6.5 ± 2.0 kJ/mol. For coplanar biphenyl with D2h-symmetry the calculated torsional energy barrier ΔE0 is 13.26 kJ/mol which is surprisingly much higher than the experimental value of 6.0 ± 2.1 kJ/mol. This discrepancy could not be resolved by optimizations assumed for two kinds of distortions of planarity of orthohydrogens from the molecular plane of the coplanar carbon atoms. But for the twisted minimum energy conformation asymmetric bending of ortho-H atoms lead to a torsional angle Φmin = 44.74° together with a dihedral angle towards ortho-H of 1.22°, and consequently even to an increase of torsional energy barriers to ΔE0 = 13.51 and ΔE90 = 6.91 kJ/mol.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080714
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Molecular orbital theory of the properties of inorganic and organometallic compounds 5. Extended basis sets for first-row transition metals (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 861-879 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A series of efficient split-valence basis sets for first-row transition metals, termed 3-21G, has been constructed based on previously-formulated minimal expansions of Huzinaga, in which each atomic orbital has been represented by a sum of three gaussians. The original Huzinaga expansions for s- and p-type orbitals (except those for 1s) have been fit by least squares to new three-gaussian combinations in which the two sets of orbitals (of the same n quantum number) share gaussian exponents. The Huzinaga three-gaussian expansions for ls and 3d atomic orbitals have been employed without alteration. The valence description of the 3-21G basis sets comprises 3d-, 4s- and 4p-type functions, each of which has been split into two- and one-gaussian parts. 4p functions, while not populated in the ground state of the free atoms, are believed to be important to the description of the bonding in molecules. The performance of the 3-21G basis sets is examined with regard to the calculation of equilibrium geometries and normalmode vibrational frequencies for a variety of inorganic and organometallic compounds containing first-row transition metals. Calculated equilibrium structures, while generally superior to those obtained at STO-3G, are not as good as those for compounds containing main-group elements only. The calculations generally underestimate the lengths of double bonds between transition metals and main-group elements, and overestimate the lengths of single linkages. Calculated normal-mode vibrational frequencies for metal-containing systems are less uniform than in those for main-group compounds.
    Additional Material: 10 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080614
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    A note on the efficient and accurate computation of the phase functions φ and χ in semiclassical approximations (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 965-971 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Efficient and accurate algorithms for the computation of two so-called phase functions which arise in semiclassical approximations are presented together with results from checks on their accuracy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080706
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Molecular modeling of polymers: I. Correct and efficient enumeration of intrachain conformational energetics (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 28-38 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Polymer conformational analyses can require being able to model the intramolecular energetics of a very long (infinite) chain employing calculations carried out on a relatively short chain sequence. A method to meet this need, based upon symmetry considerations and molecular mechanics energetics, has been developed. Given N equivalent degrees of freedom in a linear polymer chain, N unique molecular groups are determined within the chain. A molecular unit is defined as a group of atoms containing backbone rotational degrees of conformational freedom on each of its ends. The interaction of these N molecular groups, each with a finite number of nearest neighbors, properly describe the intramolecular energetics of a long (infinite) polymer chain. Thus, conformational energetics arising from arbitrarily distant neighbor interactions can be included in the estimation of statistical and thermodynamic properties of a linear polymeric system. This approach is called the polymer reduced interaction matrix method (PRIMM) and the results of applying it to isotactic polystyrene (I-PS) are presented by way of example.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080101
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Recursion formulae for calculation of overlap integrals (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1-5 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Multi-ζ Slater-type orbitals are frequently used in molecular orbital calculations. Master formulae and numerical tables are available in literature for overlap integrals between s, p, and d atomic orbitals up to principal quantum number (n) = 3 and for some other selected quantum numbers. However, no master formula or numerical table is available for quantum numbers n = 5 and above and involving ƒ orbitals. In this article recursion formulae have been presented for the calculation of the overlap integral between any two s, p, d, and ƒ atomic orbitals formed by a linear combination of Slater-type orbitals. These formulae, when expanded, would give rise to all the master formulae reported in the literature as well as formulae hitherto unreported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Ab initio studies on van der Waals molecules. A comparative study with several basis sets of the C2v HeLi2 systemThis work was financially supported by the CAICYT No. 0637/81. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 51-56 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The potential energy surface of the van der Waals system HeLi2 is computed for the case in which the system has C2v symmetry and at the Li-Li distance (5.005 bohrs). A comparative study of the results for the two methods used, ab initio Hartree-Fock and second-order Møller-Plesset, and several basis sets, ranging from minimal to near Hartree-Fock quality, is also done. The results show the importance of correcting the basis set superposition error, and the need, in order to obtain a good description of the potential, of basis sets with polarization functions on all the atoms, when the Møller-Plesset method is used. At the Hartree-Fock level, the MINI-1 basis gives results almost of the same quality as the near Hartree-Fock basis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080107
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Combination of MOMM and VEH methods to calculate electronic properties of polymers (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 107-116 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A Molecular-Orbital-Based Molecular Mechanics method (MOMM) has been employed to calculate the structures of cyclopentadiene, pyrrole, furan, thiophene, dibenzocyclopentadiene (fluorene), dibenzopyrrole, dibenzofuran, and dibenzothiophene. The dimer structures of the above compounds have also been calculated using the same method to derive the unit cells of polycyclopentadiene, polypyrrole, polyfuran, polythiophene, polydibenzocyclopentadiene, polydibenzopyrrole, polydibenzofuran, and polydibenzothiophene. The band structures, densities of states, ionization potentials, band gaps, reduction potentials, and oxidation potentials of these polymers then have been calculated by using the Valence Effective Hamiltonian method (VEH). The structural effects on electronic properties are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Quantum mechanical modeling of a transannular interaction in a bicyclic amidinium ion (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 149-157 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A transannular donor-acceptor interaction in a bicyclic azaamidinium salt was modeled by quantum mechanical calculations using a supermolecule complex consisting of a formamidinium cation and an ammonia molecule. Molecular properties are reported at various geometries. These results are compared with the results of similar calculations on the bicyclic cation itself. The model calculations and the bicyclic cation calculations are in good agreement, but both fail to reproduce the experimentally known structure. Results from ab initio calculations on the model system are discussed, as are results from calculations which included iodide as counterion.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Theoretical study on the mechanism of the thermal decarboxylation of acrylic and benzoic acids. Models for aqueous solution (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 158-169 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The mechanism of acrylic and benzoic acid decarboxylation in aqueous solution has been investigated by ab initio methods using the STO-3G and 3-21G basis sets. In those reactions, the solvent is represented successively by one and two water molecules. Their active participation as a proton relay in the chemical process is demonstrated by the large decrease in the activation energy with respect to the reaction studied in the absence of water. In the absence of any intermediate found along the reaction pathway, the proposed mechanism is the concerted process; the free acid being the species that undergoes decarboxylation via a pseudounimolecular mechanism by interaction with a chain of water molecules. At the transition state, the carboxylic hydrogen transfer to one water molecule, the reorganization of the chain of water molecules through which the proton is transferred and the cleavage of the C—C bond are much more advanced than the proton transfer from the last water molecule to the α-carbon atom of the carboxyl group.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080208
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Molecular mechanics and the deformation of macromolecules: The use of a very short cutoff combined with a quadratic approximation (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 174-184 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An approximation to the molecular mechanical treatment of structural deformations of macromolecules is presented. The method is based on a partitioning of the conformational energy into three parts. The first part is covered by the condensed potential functions which absorb many short-range nonbonding interactions. The second part consists of a few nonbonded interactions below a very short cutoff radius of 4 Å. The third part, consisting of the vast majority of pairwise interactions, is approximated by a quadratic expression confined to a subspace of the conformational space. A detailed computational example on LH-RH, including an analysis of the errors resulting from other conventional approximation methods, is given. A comparison to the conventional cutoff approximation used in x-ray refinement delivers a speedup factor of at least two orders of magnitude.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080210
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Implementation and applications of Gaussian 82 on a CDC Cyber 205 (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 324-332 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The implementation of the GAUSSIAN 82 system of quantum chemistry codes on the CDC Cyber 205 supercomputer required approximately 1 1/2 man years of effort. Idiosyncracies of the Cyber 205 architecture, operating system, and compiler in so far as they affect the conversion and operation of large quantum chemistry codes on the machine are described. While advantage has not been taken of the powerful vector processor, the high intrinsic speed of the scalar processor and the large virtual storage capacity of the Cyber 205 make it a very powerful research tool for computational chemistry. The impact of the GAUSSIAN 82/Cyber 205 combination on computational chemistry research at the University of Calgary is illustrated by brief descriptions of a range of applications from highly accurate calculations on small systems to semiempirical studies of large molecular aggregates. Complete geometry optimizations and harmonic frequency analyses, for the most part, have become routine.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080408
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    Announcement (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 562-562 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080437
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Simulation studies of branched polymer molecules (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 333-340 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Monte Carlo simulation results are presented for lattice models of uniform stars (one branch point of functionality f = 3), combs (two branch points, ƒ = 3,3) and brushes (two branch points ƒ = 3,4 and ƒ = 3,5). We estimate the critical exponent γ(ƒ), the ratio g(ƒ) = 〈SN2(ƒ)〉/〈SN2(1)〉 (where 〈SN2(ƒ)〉 is the mean-square radius of gyration of a structure having ƒ branches and N monomers), and the meansquare end-to-end branch lengths, as a function of the number and arrangement of branches. Comparisons with theoretical predictions and experimental data are made where possible, leading to a test of some predictions, and a suggestion concerning future experiments.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080409
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Configurational specificity of stacking interactions in DNA base pairs: A computational analysis (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 604-617 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A theoretical study of stacking patterns of various hydrogen-bonded base pair complexes has been undertaken. Modified Rayleigh-Schrodinger perturbation theory for intermediate range interactions, has been employed to evaluate the stacking interactions using multicentered-multipole expansion method. Net atomic charge and corresponding dipole components located at each of the atomic centers have been computed by CNDO/2 method. An analysis of the intermolecular forces involved in the stable formation of the various base pair complexes, has been presented and the results have been discussed in the light of experimental as well as other theoretical observations. The possibility of relative preference of the left-handed configuration for alternating sequences has been quantitatively explored.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080505
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...