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  • 1985-1989  (374)
  • 1905-1909
  • 1987  (374)
  • Atomic, Molecular and Optical Physics  (275)
  • Genetics  (99)
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 411-426 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report a model calculation of the transport of a local (site) excitation in a doped molecular crystal containing one impurity. We do not consider the impurity as a direct trap for electronic excitations (zero trap depth) but assume that exciton-phonon interaction is exclusively given by the coupling of excitons with the vibrational displacement of the impurity. The dynamical problem is solved by using a time-dependent effective potential consisting of equilibrium average exciton-phonon interaction and fluctuations around this average. Two correlation functions are computed using the slow phonon limit and assuming that the temperature of the system is 300 K.Transmission of the excitation energy over a distance of eight spacings takes place, electronically, within a few picoseconds. With the exciton-phonon interaction switched on, calculated correlation functions diminish very rapidly with increasing time, indicating that an irreversible transfer of excitonic energy to the thermal bath takes place. Thus transmission of the excitation energy over such a distance (and without a high rate of trapping) is not an efficient process.
    Additional Material: 5 Ill.
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  • 102
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 511-516 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The SCF method for the calculation of energy levels of triatomic molecules is applied using the hypervirial perturbative procedure for solving the coupled equations. This treatment allows to obtain in a recursive way the energy corrections and the expectation values required in the SCF treatment, avoiding the explicit calculation of the wave functions. A numerical application is made to the SO2 and O3 molecules, comparing our results with those obtained by other methods.
    Additional Material: 2 Tab.
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  • 103
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 517-545 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Similarity measures between pairs of molecular wave functions are described. They are based on the geometrical structure of the LCAO-MO framework and upon multivariate analysis ideas. The theoretical framework is presented, and formulae for some integrals needed are given. Two main measures, distance and correlation coefficients, are used. Distance and correlation matrices induce relationships in the whole MO set, which can be depicted through minimal spanning tree techniques. Furthermore, principal component analysis allows a two-dimensional visualization of the Mo manifold geometrical relationships. Various examples are given in order to obtain information on how basis set, environment, excitation, bending, stretching, and electronegativity affect the induced order. For this purpose “ab initio” SCF-LCAO-MO calculations with double- and single-zeta quality basis sets have been used for various simple molecular structures: H2O, NH3, CH4, N2, O2, C2, NO, CN, and CO. The results obtained can open the way to LCAO-MO taxonomy. Using this information, other areas of interest are connected with similarity measures (SCF and CI, localization procedures, etc.), proving in this manner their potential utility.
    Additional Material: 8 Ill.
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  • 104
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 591-594 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The time-dependent Schrouml;dinger equation for the oscillator H = α(t)p2 + β(t)x2 + γ(t)x is exactly solved. The time evolution operator is easily obtained by means of an operator algebra and the quantum-mechanical equations of motion. The problem is reduced to solving the classical equations of motion. The method is shown to apply to multidimensional oscillators.
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  • 105
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 663-667 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The upper and lower bounds of a harmonic oscillator with an octic perturbation are studied with the use of renormalized inner projection. It is shown that this relatively simple technique works even in the infinite coupling constant limit. Symbolic computation is very convenient and useful in these types of problems, where only a finite number of operations are required.
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  • 106
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 705-710 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The previously proposed local variational algorithm for generating diabatic states from adiabatic states is tested numerically for the simplest case of avoided potential curve crossing in a diatomic. The obtained results fully agree with those found by an interpolation scheme.
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  • 107
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    International Journal of Quantum Chemistry 32 (1987), S. 699-704 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Avoided crossing of adiabatic potential energy curves is considered. A new scheme for the adiabatic-diabatic transformation is developed that is based on an interpolation performed on reduced one-electron density matrices. The procedure is tested on the N2 molecule.
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  • 108
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    International Journal of Quantum Chemistry 32 (1987), S. 711-722 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Extended Hartree-Fock (EHF) equations are developed for the general open-shell case using a modified pair-orthogonality-constrained variation (POCV) method. The EHF energy is expressed in terms of corresponding orbitals that are required to remain orthogonal and paired for all arbitrary infinitesimal variations.The Euler equations for each set of orbitals are reduced to unique pseudosecular equations, the LCAO form of which may easily be derived. The Euler equations and the expressions obtained for the off-diagonal elements of the ∊γδ (γ, δ = a or b) matrices for the closed-shell case are identical to those obtained by Mayer, who used the generalized Brillouin theorem method. However, the present method yields equations for both closed- and open-shell cases and for any spin state.
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  • 109
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 110
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    International Journal of Quantum Chemistry 32 (1987), S. 47-56 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The geometries of all 12 complexes in which HF, HCl, or HBr is paired with NH3, NMeH2, NMe2H, or NMe3 are optimized with the MINI-1 basis set. As the basicity of the amine is increased via progressive methylation, or as the proton affinity of the halide is diminished, the proton equilibrium position shifts toward the nitrogen, but in no case is this shift far enough to classify the complex as an ion pair. When the effects of a polarizable medium are included via the SCRF formalism, the shift of the proton toward the nitrogen is enhanced by increases in the solute-solvent interaction such that relatively modest coupling leads to complexes of ion-pair type. In all cases, complexes containing HBr are the most sensitive to either the basicity of the amine or the influence of the medium whereas the HF analogs are affected very little.
    Additional Material: 2 Ill.
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  • 111
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In heme proteins, the axial ligands bound directly to the iron are important modulators of biological function. A common spectroscopic technique used to detect the presence of heme units with oxygen-containing ligands, is the broadening of the electron spin resonance (ESR) spectrum by hyperfine interactions with unpaired spin density in 17O-enriched systems. To be useful as a means of identifying such ligands, there must be a measurable level of unpaired spin density on the oxygen ligand. In this study, we have used the semiempirical INDO/ROHF quantum mechanical method to calculate and compare the spin density localized on the axial oxygen ligand in the active site of four model heme proteins, Metmyoglobin, cytochrome c peroxidase (CCP), P450cam, and catalase. In particular, we have attempted to determine for which systems the results of such an experiment would be a reliable indicator of the presence of water or other types of oxygen-containing ligands. Using the MetMb system, for which such broadening has been observed, to determine a threshold value of spin density on the oxygen atom needed to detect broadening of the ESR spectra, we have found one-hundredth less spin on the water ligand in P450cam, thus explaining the observed lack of broadening in the ESR spectra of the low spin resting state. In addition, we predict that the catalase system would, in principle, exhibit 17O broadening of its ESR spectra but that CCP would not. Finally, given the similarity of CCP and HRP (horse radish peroxidase), our calculations suggest that the absence of broadening in the ESR spectra of HRP does not rule out the presence of water as a sixth ligand.
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  • 112
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    International Journal of Quantum Chemistry 32 (1987), S. 325-330 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have examined an application of the weighted identification number in the QSAR study of the toxicity of aliphatic ethers on mice. The results obtained are superior to those achieved by the connectivity index.
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  • 113
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    International Journal of Quantum Chemistry 32 (1987) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 114
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    International Journal of Quantum Chemistry 32 (1987), S. 13-14 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 115
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    International Journal of Quantum Chemistry 32 (1987), S. 89-97 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio self-consistent-field electronic state calculations have been carried out for an interstitial-iron-substitutional-boron impurity pair complex in silicon. The calculations do not provide support for the currently accepted microscopic ionic model for the pair. Rather, we have shown that the covalent effects play a basic role in determining the physical properties of the complex.
    Additional Material: 3 Ill.
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  • 116
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    International Journal of Quantum Chemistry 32 (1987), S. 115-129 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By analyzing the convergence properties of the lattice sums in the exchange part of the restricted Hartree-Fock orbital energy, we isolate the source of the nonanalytic behavior of a partially occupied band at the Fermi energy. This analysis shows how an extended system behaves qualitatively differently from a finite system but also provides a possibility of following the development of nonanalyticity as the size of the system grows.
    Additional Material: 3 Ill.
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  • 117
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    International Journal of Quantum Chemistry 32 (1987), S. 163-170 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aromatic (A) and quinoid (Q) forms of polythiophene (PT) have entirely different energy gaps: ∼0.5 eV for the quinoid form and ∼2 eV for the aromatic form, respectively. The energy gaps and stability of derivatives of PT are studied by total MNDO geometry optimization using energy band theory for the total energy calculations followed by a Hückel energy band calculations to approximate the energy band structure. Addition of fused rings to PT reverses the order of stability of the aromatic and quinoid isomers and the ordering in the size of the energy gaps. Small energy gap polymers are suggested on the basis of the calculations.
    Additional Material: 3 Ill.
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  • 118
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    International Journal of Quantum Chemistry 32 (1987), S. 331-339 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton nuclear magnetic resonance (NMR) signals may be obtained from the human body in such a way as to produce images of anatomical slices. The NMR signal is mapped in the selected slice by application of field gradients which provide spatial encoding. Excellent NMR images are now obtained which are useful in clinical practice. Introduction of NMR imaging into major hospitals is proceeding rapidly, with 10 commercial companies supplying the market; over 500 whole body systems have been installed worldwide. As a method of medical imaging NMR has the advantage that it uses no ionizing radiation and is therefore inherently safe; moreover, it gives sections in transverse, coronal, and sagittal planes with equal ease, and has good tissue contrast and pathological contrast arising from relaxation time differences. Contrast may be improved by use of contrast agents. Current trends suggest that before very long, whole-body NMR systems will be found in all major hospitals.
    Additional Material: 5 Ill.
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  • 119
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    International Journal of Quantum Chemistry 32 (1987), S. 1-1 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 120
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    International Journal of Quantum Chemistry 32 (1987), S. 55-64 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 121
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    International Journal of Quantum Chemistry 32 (1987), S. 65-72 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition metal impurities in tetrahedral semiconductors are discussed, with emphasis on electronic structure results. The trends with atomic number within the 3d series, and down-the-column trends for 4d and 5d metals in III-V compounds, are considered inclusion of many-electron effects is shown to be fundamental in the description of excitation and ionization process. Finally, an unified picture of these impurity centers is drawn, with recourse to the crystal vacuum level.
    Additional Material: 5 Ill.
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  • 122
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    International Journal of Quantum Chemistry 31 (1987), S. 663-672 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iterative methods for computing eigenvalues and eigenvectors of large symmetric matrices are discussed using the language of multidimensional partitioning technique. New variants are proposed and found useful particularly for the computation of highly excited states of CI matrices.
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  • 123
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    International Journal of Quantum Chemistry 32 (1987), S. 99-103 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A particular model for the hydride Pd3FeH is studied. The linear combination of muffin tin orbitals (LMTO) method is used to calculate the electronic structure of the hydride phase of Pd3Fe and shows a drastic reduction of magnetic moments. By comparing the electronic structure of the hydride with the pure Pd3Fe, it is understood why this reduction takes place.
    Additional Material: 2 Ill.
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  • 124
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    International Journal of Quantum Chemistry 32 (1987), S. 171-180 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A derivation and formulation of density functional theory, which eliminates the formal and practical inconsistencies and limitations of previous theories and allows its extension to stationary states other than the ground state, is given. The theory presented here can also be stated as a series of three theorems that define a family of its mathematical forms, as far as the physical content of the third theorem can either be implicitly incorporated in the density functional or explicitly in the procedure to find a solution to the equations. Examples of both cases are discussed, including the statement of configuration interaction procedure in density functional form.
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  • 125
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    International Journal of Quantum Chemistry 31 (1987), S. 685-692 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An easy method of approximating the electron density of a molecule by expressing it as a sum of squares of atomic orbitals is described. The coefficients are determined by minimizing the error in the electric field. The optimal population analysis is an integration of this optimized density over the orbitals belonging to one atom. The Mulliken population analysis can be interpreted as the integral of a Mulliken density that is a similar expression with fixed coefficients. The two densities are compared in détail using calculations on the water molecule and, more briefly, HF, LiH, BH, and C2H4. The error in the densities is identified and examined. The optimal population analysis is strongly recommended as a practical improvement to the Mulliken populations.
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  • 126
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    International Journal of Quantum Chemistry 32 (1987), S. 229-237 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of light with a polyatomic system is treated as a photon-scattering process in terms of time-correlation functions of transition operators. These are written as products of factors referring only to the molecule or the light field, so that the statistical properties of the polyatomic system and the light source can be easily incorporated. This procedure is developed for resonance absorption-emission and scattering of both thermal and coherent light.
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  • 127
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    International Journal of Quantum Chemistry 32 (1987), S. 251-266 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ionizing radiations generate in matter a large number of energetic electrons, which in turn collide with molecules in matter, produce ions and excited states, and thereby degrade in energy. The description of the consequences of many collision processes to the electrons and to matter is the goal of the electron degradation theory. We summarize the current understanding of this topic, which is important as a basis of radiation chemistry and biology. In addition, we present an initial report of our new work, namely, a generalization of the Spencer-Fano theory to time-dependent cases.
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  • 128
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    International Journal of Quantum Chemistry 32 (1987), S. 307-311 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Total cross section values for electrons scattered by atoms and molecules can be obtained by adding the total inelastic cross section to the total differential elastic cross section. We compare these values with experimental values for nitrogen and carbon dioxide. For methane, we compare with experimental values from positron scattering. The agreement is excellent for nitrogen between 40 and 1500 eV and for carbon dioxide between 100 and 500 eV.
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  • 129
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    International Journal of Quantum Chemistry 32 (1987), S. 341-354 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new treatment for studying electron transfer reactions is considered. The treatment allows for a detailed description of the electronic structure and is therefore appropriate for a complete description of weakly interacting electron transfer reactions. The initial state for the electron transfer system is selected by a variational scheme. The electron transfer is pictured to take place in an encounter complex consisting of the donor, the acceptor, and (optionally) a solvent/bridge molecule. The electronic structure of the encounter complex is dynamically coupled to the surrounding solvent, and the direct time evolution of the electron transfer system is followed by a nonlinear time-dependent Hartree-Fock method. We present examples with benzeneanion radical as the donor, pyridine as the acceptor, and water as the bridge/solvent molecule. The general formalism appears to be a useful approach for studying electron transfer reactions in solution.
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  • 130
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    International Journal of Quantum Chemistry 32 (1987), S. 417-423 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We discuss the solution of the integral Dirac-Fock equation in momentum space. “Balanced” momentum-space gaussian functions are used to expand the large and small components of the Dirac 4-spinors. We show that this approach, which has been successfully used in atomic Dirac-Fock calculations, works equally well in molecular Dirac-Fock calculations.
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  • 131
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    International Journal of Quantum Chemistry 32 (1987), S. 469-473 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron propagator theory is used to calculate vertical ionization energies of closed shell anions. Third order diagonal self-energies are calculated using the post-Hartree-Fock utility subroutines of GAUSSIAN 82. Higher order corrections are estimated using the outer valence approximation. The number of operations needed rises no faster than the number required for the limited two-electron integral transformation. Basis set augmentations are made until changes in the computational results are small. Adiabatic ionization energies are obtained via many body perturbation theory calculations on the neutral potential energy surface. Applications to BeH- and MgH- give results in excellent agreement with photodetachment experiments.
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  • 132
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    International Journal of Quantum Chemistry 32 (1987), S. 435-456 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We discuss the properties of a phase space distribution function that can be expressed as a Gaussian convolution of the Wigner function corresponding to the oneelectron charge density matrix for a many-electron system. This distribution function is known as the Husimi function. It is real and nowhere negative and can be interpreted as a probability density for finding an electron in a particular coherent state or, equivalently, for finding it in a region of phase space consistent with the uncertainty principle. Information is not lost in the transformation from the Wigner function, which can be recovered. We discuss the relationships among various functions and their Fourier transforms. The Husimi function does not have the ordinary densities as marginals but rather Gaussian convolutions of them, from which the ordinary densities can be recovered. Advantages of the Husimi function over the Wigner function for the interpretation of electronic structure are discussed. Illustrative results for the hydrogen atom and for the nitrogen atom at the SCF level are presented.
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  • 133
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    International Journal of Quantum Chemistry 32 (1987), S. 533-538 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An extension of the alternant molecular orbital method to nonalternant molecules is presented. The key step involves generation of a set of localized virtual orbitals that are paired to the localized occupied orbitals (LMO'S). Each of the paired virtuals is required to occupy the same region of space as the corresponding LMO by applying a generalization of the Edmiston-Ruedenberg localization criterion. Illustrative calculations are reported for the water molecule. Using a double-zeta basis, it is found that the new paired orbital (PO) method gives approximately 20% of the available correlation energy at R = Re, 1.5Re, and 2Re. We speculate that the PO wave function may provide a good initial approximation for a subsequent many-body perturbation treatment.
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  • 134
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    International Journal of Quantum Chemistry 32 (1987), S. 563-567 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The recently developed connected moment expansions (CMXS) for the ground state energy are tested on an exactly soluble N-body problem. For a weak correlation limit the second order CMXS reproduce the correlation energy exactly, whereas for a strong correlation limit they account for half of the correlation energy. Going to higher orders, the CMX-LT approximation appears to be the most effective one. The results indicate that the CMX technique should be promising for the calculation of the correlation energy of other systems.
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  • 135
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    International Journal of Quantum Chemistry 32 (1987), S. 595-602 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Properties of the ground state (X 1Σ) of the BCl molecule are calculated in complete fourth-order many-body perturbation theory. The equilibrium bond distance is determined to be Re = 1.740 Å (Re(exp.) = 1.716 Å). Spectroscopic constants are evaluated from the potential curve and agree well with available experimental data. Static electric properties are computed by the finite-external-electric-field perturbation method. Apparently, no experimental information on these properties is available. Fully numerical Hartree-Fock results are used to estimate basis-set effects on the calculated quantities.
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  • 136
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    International Journal of Quantum Chemistry 32 (1987), S. 669-676 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While calculating zero-field splitting terms for the lowest triplet state of 4H-pyran4-thione, at the experimental geometry, it was found that the ground state was unstable with respect to an unrestricted Hartree-Fock perturbation. The smallest fragment of the molecule retaining this instability was found to be diatomic CS. The instability is dependent on the basis set used for the calculation. The instability and its relationship to basis set, equilibrium geometry, and the importance of polarization functions for second row elements has been explored for CS and H2CS as a function of internuclear distance. Minimal basis set calculations involving second row elements may be particularly prone to such instabilities.
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  • 137
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    International Journal of Quantum Chemistry 32 (1987), S. 693-698 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A displaced STO can be expanded in spherical harmonics with the coefficient functions or Löwdin a functions characterized by a C matrix. These α functions themselves may be expanded in a Taylor series that is characterized by its own E matrix. This expansion is necessary for the representation of the α function by a power series and for its evaluation about the origin. As an application, we find the power series for the molecular charge density in the vicinity of the center of a model diatomic molecule. Our analytic approach is general and yields excellent results.
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  • 138
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    International Journal of Quantum Chemistry 31 (1987), S. 927-939 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We apply completely transferable, strictly localized molecular orbitals for the calculation of molecular electrostatic fields. This approach, derived from our previous bond fragment method for the calculation of molecular electrostatic potentials, reduces computational efforts drastically. The fields around small molecules containing first- and second-row atoms are systematically overestimated as compared with ab initio calculations with a minimal STO-3G basis set. However, deviations can be corrected by a simple multiplicative factor, which means that the overall shape of the potential and field around the molecule is correctly reproduced. Our approximate field can be used to determine possible hydration sites around molecules as proposed earlier by Peinel and coworkers. Application of the method is illustrated on the formamide molecule.
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  • 139
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    International Journal of Quantum Chemistry 32 (1987), S. 79-87 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We consider the dielectric response to an acceptor ion placed at the center of a GaAs quantum well of finite depth and calculate the binding energy of heavy-hole and light-hole acceptor atoms as a function of the width of the well. We compare our values with those we have calculated from a hydrogenic approximation and find that consideration of the dielectric response of the GaAs quantum well leads to deviations with respect to the hydrogenic approximation. Specifically, we find that our binding energies are larger in magnitude than those calculated from the hydrogenic approximation. We further find that the acceptor ion binding a heavy hole is much more affected by the dielectric response of the GaAs quantum well than the acceptor ion that binds a light hole.
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  • 140
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    International Journal of Quantum Chemistry 32 (1987), S. 105-113 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The self-consistent formulation of the variational cellular method has been developed in order to calculate the electronic structure of crystals with an arbitrary number of atoms per unit cell. Applications for silicon have been carried out. Silicon, chosen here as a test case, is treated as a face-centered cubic lattice with four “atoms” per unit cell by adding empty cells. The electronic charge density was taken muffin-tin, assuming a constant value in the interstitial region between the inscribed sphere and the Wigner-Seitz polyhedrum. The spherical symmetric electronic charge density in the inscribed sphere was obtained by adding a limited number of contributions of Brillouin zone states using the “mean value point theory” developed by Baldereschi and Chadi-Cohen. Our results are in good agreement with those obtained by other methods.
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  • 141
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    International Journal of Quantum Chemistry 32 (1987), S. 153-162 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular conformations of four three-phenyl oligomers of polyaniline are determined via a CNDO/S3 molecular orbital analysis of optical absorption and valenceelectron photoemission spectra for fully hydrogenated (“Leucoemeraldine”: N-4-aminophenyl-N′-phenyl-1, 4 diaminobenzene and N-phenyl-N′-phenyl-1, 4 diaminobenzene), partially hydrogenated (“emeraldine”: N-4-aminophenyl-N′-phenyl- 1, 4-diiminobenzene), and fully oxidized (“pernigraniline”: N-phenyl-N′-phenyl- 1, 4-diiminobenzene) species. The results provide a quantitative description of the optical absorption and photoemission data.
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  • 142
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    International Journal of Quantum Chemistry 32 (1987), S. 217-227 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Self-consistent field (SCF) wave functions for CO2 are used to calculate cross sections for the elastic and inelastic scattering of fast electrons and x-rays from CO2 molecules. The effects of basis set choice and free rotation on these cross sections are investigated. The utility of an approximate scheme to correct SCF inelastic cross sections for the effects of electron correlation is examined. The probability density for the interelectronic distance, or radial intracule density, is obtained as a by-product.
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  • 143
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    International Journal of Quantum Chemistry 32 (1987), S. 751-751 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 144
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    International Journal of Quantum Chemistry 32 (1987), S. 759-760 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 145
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    International Journal of Quantum Chemistry 31 (1987), S. 73-80 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A band intensity alternation has been observed in the absorption spectra to the à 1A2″ state of NH3 and ND3 cooled in supersonic expansions. The nuclear statistical explanation for this interesting effect is given here.
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  • 146
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    International Journal of Quantum Chemistry 31 (1987) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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  • 147
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    International Journal of Quantum Chemistry 31 (1987), S. 45-55 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method is presented to analyze the IGLO (individual gauge for localized orbitals) bond contributions in 13C chemical shielding. The IGLO bond contributions calculated in the molecular frame are rotated to a local bond frame, in which one component is selected along the bond. This procedure removes the explicit angular dependence of the IGLO bond contributions and allows a comparison of the bond contributions in different molecules.The results provide a new method to study the electronic basis of shielding interactions. The problems associated with the multiple gauge origins used in the IGLO method are discussed in their relationship to the bond contribution analysis.
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  • 148
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    International Journal of Quantum Chemistry 31 (1987), S. 17-31 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have calculated reaction rates for the reactions O + HD → OH + D and O + DH → OD + H using improved canonical variational transition state theory and least-action ground-state transmission coefficients with an ab initio potential energy surface. The kinetic isotope effects are in good agreement with experiment. The optimized tunneling paths and properties of the variational transition states and the rate enhancement for vibrationally excited reactants are also presented and compared with those for the isotopically unsubstituted reaction O + H2 → OH + H. The thermal reactions at low and room temperature are predicted to occur by tunneling at extended configurations, i.e., to initiate early on the reaction path and to avoid the saddle point regions. Tunneling also dominates the low and room temperature reactions for excited vibrational states, but in these cases the results are not as sensitive to the nature of the tunneling path. Overbarrier mechanisms dominate for both thermal and excited-vibrational state reactions for T 〉 600 K. For the excited-state reaction (with initial vibrational quantum number n 〉 0) a transition state switch occurs for T 〉 1000 K for the O + HD(n = 1) → OD + H case and for T 〉 1500 K for the O + DH(n = 1) → OD + H reaction, and this may be a general phenomenon for excited-state reactions at higher temperature. In the present case the switch occurs from an early variational transition state where the vibrationally adiabatic approximation is expected to be valid to a tighter variational transition state where nonadiabatic effects are probably important and should be included.
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  • 149
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    International Journal of Quantum Chemistry 31 (1987), S. 81-90 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The balanced addition of polarization functions to the 6-31G and 6-311G basis sets for correlated wave functions is evaluated using bond energy predictions at the MP2 and full MP4 levels as a measure of correlation-balanced basis sets. The homolytic dissociations of the XH bonds in H2, CH4, NH3, H2O, and HF and the XY bonds in C2H6, NH2NH2, HOOH, and CH3OH are used as the basis for the evaluation. It is found that correlation balance is achieved for HH, XH, and XY bonds, particularly at the MP2 level, only if at least as many polarization sets, and sometimes more, are added to the hydrogens as are added to the heavy atoms.
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  • 150
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    International Journal of Quantum Chemistry 31 (1987), S. 119-131 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational motion can have a significant effect on intramolecular vibrational dynamics. In this paper, we explore the recently discovered phenomenon of rotational decoupling through both quantum mechanical and classical methods. It is found in a model system for the stretching motions of HDO, that rotational motion about the c axis can decouple the stretches. This fact can be understood as a cancellation between kinetic and centrifugal coupling as illuminated using classical resonance analysis and quantum matrix element calculations. The significance of this phenomenon is discussed in infrared multiple photon absorption experiments with specific application to isotope separation in HDO.
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  • 151
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    International Journal of Quantum Chemistry 31 (1987), S. 179-184 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 152
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    International Journal of Quantum Chemistry 31 (1987), S. 161-172 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work describes a novel trochoidal electron spectrometer and illustrates its properties on a few examples. In the first example vibrational excitation in the small molecules H2 and N2 is measured. Comparison of the results with theoretical work points to the neccessity of using non local methods for correct treatment of near-threshold region and of extremely short-lived resonances. In the second example the observation of resonant autodetachment of Feshbach resonances in many organic molecules is reported.
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  • 153
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    International Journal of Quantum Chemistry 31 (1987), S. 173-177 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Our diatomic coupled cluster method with numerical orbitals has been applied to the Ne atom. Second, third, and full fourth order MBPT correlation corrections as well as coupled cluster correlation energies are reported.
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  • 154
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    International Journal of Quantum Chemistry 31 (1987) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 155
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    International Journal of Quantum Chemistry 31 (1987), S. 187-194 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It was shown recently by the present author that the double symmetrization and the double antisymmetrization are essential in the spin-dependent and the spin-free formalisms, respectively, to perform the exclusion of all the unnecessary spin eigenfunctions and the selection of a unique set of linearly independent spin eigenfunctions. The double antisymmetrized Wigner matric basis and the Wigner double symmetrized matric basis are presented in this article for N up to 6. The double symmetrization or the double antisymmetrization also results in a direct expansion method for the calculation of the orthogonal spin coefficients; this direct method does not require the knowledge of the wave functions of the N - 1 electron system. The modified method of Graebenstetter can also be used to calculate these orthogonal spin coefficients.
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  • 156
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    International Journal of Quantum Chemistry 31 (1987), S. 243-249 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The algebra of the two-dimensional harmonic oscillator is exploited to obtain matrix elements between eigenstates of the Morse potential. This follows after mapping the latter into the radial equation of the former problem by means of a change of variable and the use of the angular variable as a dummy variable.
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  • 157
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    International Journal of Quantum Chemistry 31 (1987), S. 251-268 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 158
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    International Journal of Quantum Chemistry 31 (1987), S. 195-216 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular orbital calculations (MINDO/3) using energy minimized molecular geometries were performed on oxidized and reduced lumiflavin and related methylated isoalloxazines, including cationic and anionic species. Close agreement with experimental geometry, photoelectron spectra, and NMR data supports the importance of optimized geometries for these molecular systems and provides the basis for interpretation of chemical and biological properties. Oxidized forms are shown to be most stable in the planar configuration but also highly flexible about the N(5) - N(10) axis; only 1 kcal/mol is required for a 10° bend. N(10) is generally out of the plane slightly; also, C(9)-methyl substitution introduces nonplanarity. The unsubstituted isoalloxazine is computed to be 0.76 kcal/mol (ΔH) less stable than its isomer, alloxazine. Calculations were also performed on enol as well as quinone-methide tautomeric forms.Reduced flavin geometry depends on methyl substitution pattern: N(10) substituted forms are bent with typical fold angles around 155°, whereas the unsubstituted reduced form is planar. Both oxidized and reduced forms are also flexible.Proton affinities were calculated for protonation and deprotonation of oxidized and reduced forms. Protonation of oxidized forms is favored at N(1) by 10-12 kcal/mol and produces somewhat nonplanar isoalloxazinium ions. In addition, ΔH for the two-electron reduction of lumiflavin is estimated to be -19.7 kcal/mol.In this paper investigations of geometric aspects are presented along with introductory and background material. Orbital structure and electron distribution studies are presented in paper II.
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  • 159
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on MINDO/3 optimized geometries, molecular properties have been computed for lumiflavin and related methylated isoalloxazines. Excellent agreement with UV PES is obtained. Salient differences from previous work are identified in the interpretation of the spectra.Computed partial atomic charges are presented and discussed for both oxidized and reduced forms, including cationic and anionic species. The most polar portion of the isoalloxazine system is pyrimidine-like ring C because of the high polarity of the carbonyl groups. Otherwise, N(1) and N(3) are the most negative ring atoms in the oxidized and reduced forms forms; C(4a) is also very negative in reduced forms. N(5) and N(10) are more negative in reduced than in oxidized forms. It is shown in two-electron reduction that bond length changes are quite localized to the diazadiene portion of the molecule, but that changes in partial charges extend to rings A and B. Only the O=C—NH—C=O moiety does not experience much change in charge.Good correlation is obtained between MINDO/3 partial charges and proton NMR for both the aromatic and methyl protons on ring A, supporting the assignments by Grande and Müller. Also changes in 13C NMR spectra upon reduction are paralleled by changes in computed partial charges. The nature of two-electron reduction is analyzed in terms of changes in HOMO/LUMO as well as geometry and charge distribution. A table of computed properties is included for all compounds studied: total energy, ΔHƒ, ionization potential, electron affinity, and dipole moment.
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  • 160
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    International Journal of Quantum Chemistry 31 (1987), S. 269-278 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The method of statistical exchange-correlation parameter is presented. It has been shown that there is only a small difference between the self-consistent, the statistical, and the αHF parameters. We suggest using statistical exchange-correlation parameters in molecular calculations.
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  • 161
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    International Journal of Quantum Chemistry 31 (1987), S. 279-285 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that the method of Adamowicz for basis sets reduction [Int. J. Quantum Chem. 19, 545 (1981)] is, in practice, a particular case of the method of maximum overlap. The relationships between these two methods are discussed analytically and by means of a simple numerical example.
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  • 162
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    International Journal of Quantum Chemistry 31 (1987), S. 295-307 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relativistic multiple scattering Xα method has been applied in order to calculate the eigenvalues and the charge densities of cis and trans diaminodichloroplatinum(II). The activity of the cis isomer as an antitumor agent is discussed in terms of the possible modes of coordination of certain fragments of the DNA molecule through the LUMO state of the cis Pt complex. Although possible, coordination of the trans isomer is rendered unlikely as a result of possible strain effects.
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  • 163
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    International Journal of Quantum Chemistry 31 (1987), S. 287-293 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An article by Coulson on the relationhship of physics and mathematics has attracted our attention to problems already discussed by Titchmarsh, namely the distribution of quantum energy levels of a particle confined in a square or a cube with infinite potential-energy walls. These problems are identical to some classical problems in the theory of lattice points, which belongs to number theory. They are seemingly simple, but in fact they are very difficult and not yet completely solved. We summarize the most relevant results from number theory. Whereas the beautiful theorems bearing directly on the error with respect to elementary estimates only provide indications concerning the order of that error; theorems concerning mean values can be used as a basis for a physicist's guess on its asymptotic mean value.This paper has also been intended to contribute to bridging the gap between quantum mechanics and number theory.
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    International Journal of Quantum Chemistry 31 (1987), S. 327-327 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 31 (1987), S. 325-325 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 31 (1987), S. 329-329 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 167
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    International Journal of Quantum Chemistry 31 (1987) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 168
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    International Journal of Quantum Chemistry 31 (1987), S. 331-331 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 169
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We developed a theoretical method for studying the aromatic stability of large molecules, molecules having a dozen and more fused benzene rings. Such molecules have so far often been outside the domain of theoretical studies. Combining the statistical approach and a particular graph theoretical analysis, it is possible to derive the expressions for molecular resonance energy for molecules of any size. The basis of the method is enumeration of conjugated circuits in random Kekulé valence structures. The method has been applied to evaluation of the resonance energies of conjugated hydrocarbons having about a dozen fused benzene rings. The approach consists of (1) construction of random Kekulé valence structures, (2) enumeration of conjugated circuits within the generated random valence structures, and (3) application of standard statistical analysis to a sufficiently large sample of structures. The construction of random valence forms is nontrivial, and some problems in generating random structures are discussed. The random Kekulé valence structures allow one not only to obtain the expression for molecular resonance energies (RE) and numerical estimates for RE, but also they provide the basis for discussion of local molecular features, such as ring characterization and Pauling bond orders.
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  • 170
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    International Journal of Quantum Chemistry 32 (1987), S. 123-131 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various isomers of CH3(H2O)n+ (where n = 1-3) have been studied using self-consistent field gradient techniques. The calculations have largely employed a split valence (4-21G) basis set, although the effects of polarization functions and electron correlation have been considered for a model system. A mechanism for the formation of CH3OH from CH3(H2O)n+, involving linear hydration chains, is proposed, and the relevance of the results to the various proposed pathways for the decomposition of nitrosamine metabolites is discussed.
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  • 171
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    International Journal of Quantum Chemistry 32 (1987), S. 165-179 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular path codes are computed for 17 hydrocarbons, including benzenoid alternant, nonbenzenoid alternant, fully aromatic nonalternant, antiaromatic nonalternant, and monoradical hydrocarbons. Comparability conditions of Randić and Wilkins [9-18] based on the theorems of Muirhead and Karamata are imposed on the partial sums of the codes. The distance/similarity matrix is constructed using the individual paths as projections in Euclidean space. Both resonance energies and total pi energies correlate with partial ordering predicted from both comparability and similarity schemes. The normalized codes succeed in discriminating combinatorial properties of the various topologies studied such as conjugated circuits.
    Additional Material: 9 Ill.
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  • 172
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed analysis of the ΔE(R) curves for nine hydrogen bonded dimers involving HF, H2O, and NH3 as partners, computed with five basis sets (STO-3G, MINI-1, 3-21G, 4-31G, and 6-31G**) and subjected to counterpoise (CP) corrections with three different methods is reported. Using several criteria and tests, the positive effect of full CP corrections for the description obtained with all the basis sets (with the exception of the STO-3G one) is pointed out. The CP correction at the 6-31G** levels is still sizable and improves the results with respect to the estimated Hartree-Fock limits of ΔE(Req) and Req. The results obtained with the application of the full CP correction to the MINI-I energies are of relatively good quality. The STO-3G energies at the SCF level are, on the contrary, overcorrected by the full CP correction and slightly improved by “limited” CP corrections: this basis set, however, is not recommended for calculations of geometries and stabilization energies of H-bonded dimers of this size.
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  • 173
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    International Journal of Quantum Chemistry 32 (1987), S. 295-312 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An accurate analytical electron density for the beryllium atom is obtained by using a fast and systematic method recently developed and tested for the neon atom. Asymptotic conditions both at the nucleus and at large distances are obeyed. A point-by-point comparison between our density and the one obtained from an almost “exact” configuration interaction wave function shows that differences are less than 0.5% for r between 0 and 5 bohrs and less than 1 % up to 9 bohrs. The accuracy of the density is also assessed by comparing results of density moments and x-ray scattering factors.
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  • 174
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    International Journal of Quantum Chemistry 31 (1987), S. 425-427 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is made clear that two different statements in the literature concerning energy derivatives are completely compatible by deriving them as two different interpretations of the same equation. Some other aspects of these results are also discussed.
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  • 175
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    International Journal of Quantum Chemistry 32 (1987), S. 407-408 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 176
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    International Journal of Quantum Chemistry 32 (1987), S. 405-406 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 177
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    International Journal of Quantum Chemistry 32 (1987), S. 435-450 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The locality of conformational state with relation to the asymmetry in potential is proved. The adequacy of harmonic approximation of conformation wave function is discussed. Then, on the grounds of the rigorous definition of the conformation-vibrational state, the role of vibration in the information transmission and cooperativity is discussed by the calculation of statistical mechanics. In the rest of this article, the conformational change as a quantum transition is investigated in detail. The viewpoint of conformational transition with respect to electronic motion is stressed. On the basis of proposed selection rules, the approach to the conformational change that consists if multiple steps is clarified.
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  • 178
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The computational procedure for reconstructing a many-electron wave function on the basis of x-ray diffraction data of one-electron density is proposed within the method of local-scaling transformations.
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  • 179
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    International Journal of Quantum Chemistry 32 (1987), S. 473-489 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rigorous derivation of the energy density functional is proposed within the framework of the spinfree, or spin-restricted formulation of the energy density functional theory. It is shown particularly that the kinetic energy density functional is given by a sum of the Weizsacker term and the so-called “modified” Thomas-Fermi one. The variational principle is formulated for the energy density functional theory in terms of the Euler-Lagrange equation, and the virial theorem is proposed.
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  • 180
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    International Journal of Quantum Chemistry 31 (1987), S. 463-470 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Valence-bond calculations are reported for the isoelectronic series of molecules and ions: N2, CO, BF, NO+ and CN-. The most important structures are N≡N, C=O, Bπ—F, N+=O and C=N. Hybridization of the 2s and 2p orbitals is important. Only two or three structures are required to obtain an energy lower than that obtained with the molecular orbital approximation. Structures in which the electronegative element loses a σ-orbital or gains a π-orbital are favored. π-bonds tend to be favored over σ-bonds. The bond in NO+ resembles that in CO, whereas that in CN- resembles the bonding in N2.
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  • 181
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    International Journal of Quantum Chemistry 31 (1987), S. 471-487 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio SCF, CI, CEPA, and MCSCF techniques are compared and contrasted in a theoretical study of the 1s core ionized Li2 molecule from the point of view of core hole localization. In agreement with earlier studies of symmetric core ionized molecules, SCF theory is found to give a physically reasonable description of core ionization only when symmetry breaking is allowed. This results in a dramatic lowering of the energy of the core ionized state and hence of the ionization potential. By extension, CI wave functions that are developed in terms of a broken symmetry SCF reference plus its single and double excitations are found to perform significantly better than those constructed from symmetry adapted SCF orbitals. Alternatively, if the full point group symmetry is to be retained, a multiconfigurational treatment is called for and, in agreement with the conclusions of an analogous study on O2 [H. Ågren, P.S. Bagus, and B.O. Roos, Chem. Phys. Letters 82, 505(1981)], it is found that a modestly sized MCSCF wave function is capable of accounting for the energetic effects of symmetry breaking. Potential energy curves for Li2 and several states of core ionized Li2 have been calculated, allowing predictions of the adiabatic ionization potential and vibrational, satellite, and Auger structures in the photoelectron spectrum of Li2 to be made.
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  • 182
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    International Journal of Quantum Chemistry 31 (1987), S. 489-505 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A practical algorithm is described for generating a set of symmetry- and spin-adapted antisymmetrized products of molecular orbitals (SAAPs) which form an orthogonal basis for a full active configuration space. The spin-adaptation is completely general. The space-symmetry adaptation is accomplished for the groups C∞v and D∞v.
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  • 183
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    International Journal of Quantum Chemistry 32 (1987), S. 9-14 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the study of cancer as a complicated disease caused by many combinations of various factors, it may be of importance to consider also any possible changes of the water structure in the environment of the malignant cells. The occurrence of such changes has been established experimentally, for example, by a study of the magnetic properties of water by nuclear magnetic resonance (NMR) spectra. It has been found that the protons in the water surrounding malignant cells have a much longer spin-lattice relaxation time than the protons in the water around normal cells. This indicates that the water molecules in tumor cells are less structured and able to move more freely than in normal tissues, where, due to the effect of hydrogen bonding, water occurs mainly as five- or six-membered rings. This prolongation of the proton spin-lattice time may be an important factor in cancer, but further studies are necessary before one can decide with certainty whether it would be possible to use this effect to diagnose malignant transformations at an early stage. It is suggested that changes in the magnetic properties of water in a malignant tumor during chemotherapy and other treatments be monitored as control tools.
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  • 184
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    International Journal of Quantum Chemistry 32 (1987), S. 15-25 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A theoretical exploration of the intercalative mode of binding with DNA of the antitumor drug bisantrene and the closely related but inactive drug LC 230487 indicates that both drugs show a preference for a major groove intercalation to GC sequences. In this mode of binding bisantrene is predicted, however, to have a greater affinity for DNA than LC 230487 due to a stronger and somewhat different network of H-bonding interaction with the double-stranded receptor. While this difference in the strength and pattern of the intercalative association could be considered as possibly related to the striking difference in their antitumor activity, the experimental observation that both compounds exhibit a practically indentical affinity constant for binding to DNA, confronted with the theoretical evaluation of different affinities for intercalative association suggest that LC 230487 could possibly interact with DNA by a different mechanism which does not lead to antitumor activity. This could perhaps consist of an exterior binding.
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  • 185
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    International Journal of Quantum Chemistry 32 (1987), S. 57-64 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bimolecular hydroxyalkylation of the N2, 3-, O6, and 7-position of guanine by protonated oxirane has been studied using the MNDO molecular orbital procedure. The enthalpies of activation (relative to the isolated reactants) were calculated to be 12.5, 11.4, -4.8, and -4.9 kcal mol-1, respectively. The transition state geometries were characteristically SN l-like. The forming bonds reach ca. 0-2% of their final strengths while cleavage of the breaking bonds is ca. 77-87% complete. Their relative energies are dominated by electrostatic interactions between the reacting moieties with little to no charge transfer involved. The relevance of these results to the reactions of carcinogenic oxiranes and their derivatives with nucleic acids is discussed.
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  • 186
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    International Journal of Quantum Chemistry 32 (1987), S. 65-74 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular dynamics free energy perturbation method was applied to study the solvation effect on the tautomeric equilibria in water solution as well as association of the nucleic acid base pairs in water solution and in vacuo. Tautomerization energies in vacuo calculated by the ab initio SCF-HF method differed from experiment by 1-2 kcal/mol, even if geometry optimization was performed and MP2 correlation energy calculated at 6-31G* basis set was added.
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  • 187
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    International Journal of Quantum Chemistry 32 (1987), S. 281-288 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The scope of multistep modeling (MSM) is expanded by adding a least-squares minimization step in the procedure to fit backbone reconstruction consistent with a set of C-alpha coordinates. The analytical solution of Phi and Psi angles, that fits a C-alpha x-ray coordinate [1] is used for tyr-tRNA synthetase. Phi and Psi angles for the region where the above mentioned method fails, are obtained by minimizing the difference in C-alpha distances between the computed model and the crystal structure in a least-squares sense. We present a stepwise application of this part of MSM to the determination of the complete backbone geometry of the 321 N terminal residues of tyrosine tRNA synthetase to a root mean square deviation of 0.47 Å from the crystallographic C-alpha coordinates.
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  • 188
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    International Journal of Quantum Chemistry 32 (1987), S. 167-188 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mobile protons in water bound at the interface with the membrane are analogous in a number of respects to the conduction electrons in a thin layer of metal spread on the surface of a dielectric. The hypothesis analyzed in this paper is that such mobile hydrogen bonds may be paired by propagating electronic oscillations in polar side groups of the membrane. The model is dual to the BCS theory of electronic superconductivity in that (1) the mobile H+ bonds play the role of conduction electrons and (2) the pairing interaction has its origin in electronic excitations rather than lattice vibrations. The pairing mechanism is similar to that in Little's proposed room temperature organic superconductor, except that it involves transient alterations in ground state energies of polarizable electrons in a colorless membrane rather than polarization of dye-like side groups. Numerical estimates based on formulae applicable to metallic superconductors show that condensation of proton pairs would be feasible in small connected domains on the membrane surface if the water structure is closely packed and the effective mass of the protons sufficiently reduced (though significant disanalogies between the bound water and metal cases make the quantitative applicability of these formulae unlikely). Some of the factors that favor a superfluid transition are high salt concentration, polarizable macromolecules on the membrane that increase the three-dimensionality of the interaction, and the presence of proton donors and acceptors other than oxygen. The dynamic order inherent in a proton superflow could provide the basis for a wide variety of highly ordered motions in biological systems.
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  • 189
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We consider the problem of location an active fragment (substructure) common to a class of biologically active compounds and presumed responsible for their biological activity (therapeutic or toxic). Our approach is graph-theoretical in that molecules are represented by suitable graph-theoretical invariants. Specially weighted paths in the molecular graph are adopted as descriptive elements. By selecting different sets of atoms one searches for a fragment that best represents the relative activities of the compounds. As an illustration we consider a dozen nitrosamine mutagens and analyze the cases of five-, six-, and sevenatom fragments. The approach clearly indicates that a specific seven-atom fragment (for molecules with up to 11 nonhydrogen atoms) can account for the relative mutagenic activities of the nitrosamines considered.
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  • 190
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    International Journal of Quantum Chemistry 32 (1987), S. 317-324 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The HeI photoelectron (PE) spectra of the drugs antipyrine (phenazone, 1), aminopyrine (amidopyrine, 2), phenylbutazone (3), and indomethacin (4) are reported. These drugs possess analgesic-antipyretic and anti-inflammatory activity, and have been in clinical use for many years. Their electronic structure, which is important to their biological activity, is determined by the application of composite molecule methods to an analysis of the PE spectra.
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    International Journal of Quantum Chemistry 32 (1987), S. 341-345 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 192
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    International Journal of Quantum Chemistry 32 (1987), S. 3-11 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 193
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    International Journal of Quantum Chemistry 32 (1987), S. 31-44 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A first-principles theory for the band gaps and electronic excitation energies in crystals is described. Optical and photoemission spectra are properly interpreted as transitions between quasiparticle states of the many-electron system. The theory requires adequate treatment of the Coulomb interaction between the electrons, including exchange and dynamical correlation effects. The nonlocal energy-dependent electron self-energy operator is evaluated from first principles using the full dielectric matrix and the dressed Green's function. Quasiparticle energies for materials covering a wide range of metallicity and ionicity are presented. With no empirical input, the calculated band gaps, optical transition energies, and band dispersions are all within a few percent of experimental values. For semiconductors and insulators, we find that local field effects in the screening of the Coulomb interaction and dynamical renormalization are both crucial for accurate results. The present method also extends beyond the case of bulk crystals, e.g., to surfaces. Results on the surface state energies of the Ge (111): As and S(111):As surface are discussed and compared with experiment.
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  • 194
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    International Journal of Quantum Chemistry 32 (1987), S. 73-78 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using the Haldane-Anderson formalism we study the possibility of obtaining a negative U system for transition metal impurities in semiconductors. We propose, even without including electron-lattice interaction, the occurrence of negative-U as a consequence of the impurity-host hybridization to explain why some oxidation states would be missing in these systems.
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  • 195
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    International Journal of Quantum Chemistry 31 (1987), S. 673-684 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An interative technique to solve nearly singular systems of linear equations of quantum chemical interest is described and tested. The solution is split into regular and singular parts, the last being the resonating eigenvector.
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  • 196
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    International Journal of Quantum Chemistry 32 (1987), S. 137-151 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An iterative transfer perturbation method is applied to polyacetylene under some kinds of local perturbations at the level of the extended Hückel method. This method rapidly provides the electronic states of nonperiodical polymers with good accuracy.
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  • 197
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    International Journal of Quantum Chemistry 32 (1987), S. 181-190 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A dynamical partitioning of the reaction field is proposed in order to study the electron density flow along the reaction coordinate. The density functional is constructed in a universal form, and a one-to-one correspondence is established between the density matrix and the electron density. The density functional is free from the constraints of N or v representability and is treated as a thermodynamic function that obeys the principle of maximum entropy. The functional derivative of the density functional with respect to the electron density is introduced as a response operator. The reaction paths are combinations of the dynamical processes of the electron density; the corresponding response operators and new type of thermodynamic functions and potentials are defined and shown to be useful. The characteristic features of the chemical reaction coordinate is discussed in terms of the new thermodynamic quantities. The importance of the softest vibrational mode as the chemical reactivity index is rationalized in terms of the density functional theory.
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  • 198
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    International Journal of Quantum Chemistry 31 (1987), S. 695-696 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 267-282 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrogen addition to acetylene has been studied by molecular orbital methods with the unrestricted Hartree-Fock (HF)approach and with Møller-Plesset (MP) perturbation theory up to fourth order using the 6-31G*, 6-31G**, and 6-311G** basis sets. For each basis set a number of points along an approximate reaction path were calculated by fixing the attacking H—C distance and optimizing all of the remaining parameters. At these geometries, single point MP4 calculations with and without spin projection were carried out, yielding the position, height, and shape of the addition barrier at the various levels of calculation with each of the three basis sets. The results of this approach were confirmed by a grid search of the region near the transition state using the 6-31G* basis set. The unprojected MP2, MP3, and MP4 barriers are too narrow and are 10-20 kcal/mol too high. With spin projection, the barriers are much lower and broader. At the PMP4SDTQ/6-311G** level, with zero point energy calculated at UHF/6-31G*, the vibrationally adiabatic barrier at 0 K is 4.0 kcal/mol, and the attacking H—C distance is 2.0 Å.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 200
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 313-319 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We explore the implications of static disorder on electron transfer (ET) in a microscopically inhomogeneous polar medium, where the environment of each solute is characterized by a single dielectric relaxation time, τ, with the distribution function of τ being related to the complex dielectric susceptibility. For the interesting situation of solvent-controlled ET, the decay of the population probability is nonexponential, which can be expressed in terms of a cumulant expansion. The microscopic decay function can be related to the macroscopic step-response function of the dielectric medium.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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