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  • 1995-1999  (27)
  • 1980-1984  (277)
  • 1890-1899
  • 1997  (27)
  • 1980  (277)
  • Atomic, Molecular and Optical Physics  (304)
  • 1
    Electronic Resource
    Electronic Resource
    Noninteger principal quantum numbers increase the efficiency of Slater-type basis sets (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 1-11 
    Details
    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: Roothaan-Hartree-Fock (RHF) calculations are carried out for the ground states of the atoms from helium to xenon using a minimal basis set of Slater-type functions whose principal quantum numbers are allowed to take variationally optimal noninteger values. The resulting energies are substantially superior to those obtained previously under the usual restriction that principal quantum numbers be positive integers. The energy lowering relative to the single-zeta wave functions of Clementi and co-workers ranges from 0.0066 Eh in He to 11.2 Eh in Xe. Our results are superior to those obtained by Höjer using a minimal basis set of unconventional binomially screened basis functions. Noninteger principal quantum numbers benefit d-orbitals the most; physically realistic negative d-orbital energies are obtained in all cases including those transition-metal atoms for which a conventional single-zeta STF basis leads to positive d-orbital energies. © 1997 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Ab initio study on the reaction of Sc+ + CH4 → Sc+(SINGLE BOND)CH2 + H2 (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 23-27 
    Details
    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 ab initio study on the reaction of the ground state (3D) and the excited state (1D) of Sc+ with methane was performed. Reaction channels on the singlet and triplet potential surface (PES) and the reaction mechanism are examined and discussed. Three regions of the potential surface was studied: the molecular complex, the C(SINGLE BOND)H insertion products, and the transition states for the reaction. Comparisons between singlet and triplet PESs show that the excited state (1D) of Sc+ has more reactivity with methane than does the ground state (3D) due to the spin quantum number conservation with the more stable insertion intermediate. © 1997 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of hybridization displacement charge on the description of electrostatic potentials of molecules with multiple electrophilic sites (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 67-76 
    Details
    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 importance of the hybridization displacement charge (HDC) in describing molecular electrostatic potential (MEP) maps was demonstrated by studying six molecules; pyrazine N-oxide, para-nitropyridine, 5-nitropyrimidine, 3-nitropyridazine, N2, and N2O. It is shown that continuously distributed HDC-corrected Löwdin charges reproduce the MEP features of these molecules, most of which have competing electrophilic sites, in agreement with ab initio results. Further, it is found that for homonuclear diatomic molecules MEP minima can be located properly using HDC-corrected Löwdin (or HDC-corrected Mulliken) continuously distributed charges, but these features cannot be obtained using the conventional Löwdin (or Mulliken) charges. It was shown that the order of molecular electric field (MEF) values near the different electrophilic sites becomes changed when one moves away from the molecules. Thus, pyridine-type nitrogen atoms are the preferred binding sites close to the molecules, while at large distances, effects of oxygen atoms of the NO groups become dominant. © 1997 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Crystalline and local vibrations of paired bases in poly(dG)-poly(dC) interacting with the h-b-1 hydrogen bond (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 115-124 
    Details
    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: Some types of atomic vibrations in a chain of the DNA type constructed of G-C pairs were studied. These are the atomic vibrations of the lateral groups of guanine and N(3)H(1)H(2) of cytosine connected by the hydrogen bond h-b-1 and the vibrations of the centers of masses of bases in the direction parallel to bonds h-b-i, i = 1-3. The vibrations mix partially due to the dependence of the energy of the bond h-b-1 on its length and split into two bands because of the interaction between neighboring base pairs. It was shown that the excitation of the bond h-b-1 results in the splitting off of the two local vibrations and in a small deformation of the chain in the vicinity of the pair with the localized hydrogen bond. The law of the dispersion of band vibrations, values of the split-off frequencies, and degree of poly(dG)-poly(dC) chain deformation were determined. © 1997 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of screened nuclear attraction and electron repulsion molecular integrals over Gaussian basis functions (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 273-278 
    Details
    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: Analytical solutions to the Yukawa-like screened Coulomb nuclear attraction and electron repulsion molecular basic integrals, as well as to the basic integrals required to compute the virial coefficient, over Gaussian basis functions, are derived and cast into a practical closed form, suitable to interface with modern codes for the calculation of molecular electronic structure. © 1997 John Wiley & Sons, Inc.
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  • 6
    Electronic Resource
    Electronic Resource
    Photoelectron spectra of molecules. II. Carboxylic acids and their esters (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 303-314 
    Details
    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: He I photoelectron (PE) spectra of four carboxylic acids and five esters are measured. Semiempirical and ab initio quantum chemical calculations are used for the interpretation of the spectra. The complex approach which uses empirically established relationships (the dependence of valence electron ionization energies on proton affinities in the gas phase, on the core level ionization energies, and on the structure) was developed. © 1997 John Wiley & Sons, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    Molecular orbital analysis of chemical carcinogens (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 323-328 
    Details
    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: Simple molecular orbital calculations are employed in searching electronic parameters which may characterize the chemical carcinogens. Using frontier orbitals, the carcinogen-DNA bond formation is described as an electron transfer from the highest occupied molecular orbital (HOMO) of DNA to the lowest unoccupied molecular orbital (LUMO) of the carcinogen. Analysis of the DNA bases units shows that the electron donation occurs preferentially at the guanine site. The calculated low LUMO energy of several carcinogens indicate correctly the electrophilic character of these compounds. The difference between the carcinogen and the ultimate carcinogen is analyzed. Epoxides, free radicals, alkylating agents, and other metabolite forms are studied. A reasonable correlation is found between the LUMO energy and the carcinogenic function. © 1997 John Wiley & Sons, Inc.
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  • 8
    Electronic Resource
    Electronic Resource
    Generalized relativistic effective core potential: Gaussian expansions of potentials and pseudospinors for atoms Hg through Rn (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 63 (1997), S. 1107-1122 
    Details
    ISSN: 0020-7608
    Keywords: relativistic pseudopotentials ; heavy atoms ; method of molecular calculation ; electronic structure ; Gaussian approximation ; Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Gaussian expansions of the generalized relativistic effective core potential (GRECP) components are reported for elements Hg through Rn. The accuracy of the analytical GRECPs is estimated by calculations of atomic transition energies with the numerical one-configurational wave functions in comparison with Dirac-Fock calculations. The results of the corresponding calculations with the RECPs of other groups are also given. An “averaged error” in the reproduction of the transition energies without the change of the occupation number of the 5d-shell is an order of magnitude smaller than that for the RECPs of other groups. As is demonstrated for the transitions with the change of the occupation number of the 5d-shell in mercury, the largest absolute error of the GRECP is only 1.5-2 times smaller than that of the energy-adjusted pseudopotential (PP) or the RECP of Ross et al. with the same space of explicitly treated electrons. However, the dispersion of these errors is 19⋅10-4 au for the energy-adjusted PP, 35⋅10-4 au for the RECP of Ross et al. and only 4⋅10-4 au for the GRECP. One-configurational spin-averaged calculations of the molecular properties for HgH and HgH+ are carried out and compared with the corresponding results of Häussermann et al.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 1107-1122, 1997
    Additional Material: 17 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulation of the free surface of liquid formamide (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 63 (1997), S. 1123-1131 
    Details
    ISSN: 0020-7608
    Keywords: MD simulations ; liquid surface ; formamide ; molecular orientation ; molecular surface density ; Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular dynamics simulations of liquid formamide(HCONH2) were carried out using the GROMOS software. The formamide molecule is represented by all of its atoms with all internal degrees of freedom. In contrast to other simulations dealing with bulk properties, this study focuses on the interface liquid-vacuum for the first time. We show that the molecular plane is tilted out of the surface, exposing the HCO group to the vacuum.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 1123-1131, 1997
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  • 10
    Electronic Resource
    Electronic Resource
    Theoretical study on Pd dimer and trimer interaction with the hydrogen molecule (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 29-45 
    Details
    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 H2 interaction with the Pd dimer and trimer were studied using multiconfigurational self-consistent field (MC-SCF) calculations with the relativistic effective core potential (RECP); the correlation energy correction was included in the extended multireference configuration interaction (MRCI), variational and perturbative to second order. Here, we considered the Pd2 first six states: 3Σ+u, 1Σ+g, 3Πg, 3Δxy, 1Σ+u, and 3Σ+g. For them, the four geometrical approaches included were the side-on H2 toward Pd2, for the hydrogen molecule in and out the Pd dimer plane; the perpendicular end-on H2 toward Pd2; and the perpendicular end-on Pd2 to H2. The Pd2 ground state is 3Σ+u, which only captures H2 in the C2v end-on approach, softly relaxing the H(SINGLE BOND)H bond. The closed-shell 1Σ+g captures the H2 molecule in all the approaches considered: The side-on approach of this state presents deep wells and relaxes the H(SINGLE BOND)H bond, and the end-on approach captures H2 with a relatively longer H(SINGLE BOND)H distance and also a deep well. The 3Πg state was the only one which did not capture H2. For the triangular Pd3 clusters, H2 was approached in the C2v symmetry in and out of the Pd3 plane. In the triangular case, H2 was absorbed in both spin states, with deep wells and relaxing the H(SINGLE BOND)H distance. The linear Pd3 singlet and triplet states capture outside of the Pd3 and break the H(SINGLE BOND)H bond. © 1997 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    Total and partial decay widths in vibrational predissociation of the HeI2 van der Waals complex for lower initial vibrational excitations (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 89-96 
    Details
    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 presented a calculation of the total and partial decay widths of vibrational predissociation (VP) of the HeI2 molecule for low initial vibrational excitations from the lowest van der Waals (vdW) state with total angular momentum J = 0. A time-dependent golden rule wave-packet method was employed in our numerical calculations for the decay widths. The computed total decay widths, lifetimes, and rates of VP are in fairly good agreement with those extrapolated from the experimental data available. Predicted total decay widths as a function of initial vibrational levels exhibit a highly nonlinear behavior. These results demonstrate that a quantum mechanical decay mode for low vibrational excitation remains as well. The total propagation time needed in the time-dependent golden rule wave-packet calculations is much shorter than is the lifetime of the predissociation of HeI2. It is shown that the final-state interaction between the fragments is important for determining the final rotational-state distribution (partial decay width). We find that the major peak position in the final rotational-state distribution shifts to lower rotational energy levels with increase of the initial vibrational quantum number, which is evidently different from that for higher vibrational levels. This fact can be clearly explained by the dependence of the amount of kinetic energy released to the product degrees of freedom on the initial vibrational state. © 1997 John Wiley & Sons, Inc.
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  • 12
    Electronic Resource
    Electronic Resource
    A very accurate grid method for the solution of Schrödinger equations: The helium ground state (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 63 (1997), S. 1065-1078 
    Details
    ISSN: 0020-7608
    Keywords: very precise eigenvalues ; very accurate grid method ; general solution for Schrödinger equations ; rapidly convergent treatment for helium eigenvalues ; superconvergence ; optimization of grids ; treatment of continuum ; Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An extension to the theory of Schrödinger equations has been made which enables the derivation of eigenvalues from a consideration of a very small part of geometric space. The concomitant unwanted continuum effects have been removed. The theory enables very convergent or “superconvergent” calculations. In the case of the helium ground state, E=-2.90372437703411987 Eh was obtained from 251 terms. The result is comparable to that from the largest variation calculations so far carried out reinforced by extrapolation techniques. The theory is extensible to atoms and molecules irrespectively of the number of electrons or nuclear centers. In these cases, the advantage of “superconvergent” calculations will be more pronounced than in the case of helium.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 1065-1078, 1997
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  • 13
    Electronic Resource
    Electronic Resource
    Resonances and antibound states in a Morse potential (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 239-244 
    Details
    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 calculate the resonant and antibound state energies for a Morse potential with a centrifugal barrier using Siegert boundary conditions. Starting with a complex wave number k (purely imaginary for bound and antibound states), we integrate numerically from the origin up to a matching point using Numerov's method. The inward integration is performed using the corresponding (first-order) Riccati equation. The complex eigenvalues are found by matching the two logarithmic derivatives. We find narrow shape resonances within the well, above the dissociation limit, and broad resonances above the centrifugal barrier. Antibound states are found even with J = 0. © 1997 John Wiley & Sons, Inc.
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  • 14
    Electronic Resource
    Electronic Resource
    On the dynamics of a linear and a nonlinear quantum oscillator with randomly changing harmonic frequency (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 265-272 
    Details
    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: Numerical experiments with a nonlinear (λχ4) oscillator which has its harmonic frequency changing randomly with time reveal certain interesting features of its dynamics of quantum evolution. When λ = 0, the level populations are seen to oscillate. But, as the nonlinear coupling is switched on (λ 〉 0), a threshold is reached at λ = λc when the evolution is seen to be characterized by an abrupt transition dominantly to the highest available state of the unperturbed (initial) oscillator. It is shown that this transition probability is maximized at a particular value of λ. The time threshold for this transition decreases with increasing nonlinear coupling strength. The numerically obtained structures of the underlying quantum-phase spaces of the linear and nonlinear random oscillators are examined. Possible use of these results in a problem of chemical origin is explored. © 1997 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Electronic structure of testosterone: A semiempirical and ab initio assessment (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 279-289 
    Details
    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: Testosterone (17β-hydroxy-4-androsten-3-one) was studied by the semiempirical AM1 and PM3 and ab initio STO-3G*, 3-21G*, and 6-31G* methods. The goals were to compare those methods and to know the electronic structure of the hormone. Full geometry optimization was performed, and two crystal conformers (T1 and T2), and experimental dipole moment in solution were used for comparison. One conformer with a dipole moment similar to the solvated conditions was generated. Total energy, entalphies, dipole moments, charges, electrostatic potentials, and highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbital (LUMO) were calculated. Root-mean-square (RMS) index of the theoretical molecules against T1 and T2 showed best results with the 3-21G* and 6-31G* methods, while AM1 gave better energies than PM3. Dipole moments were directed toward the OH group and the botton face of the A ring. The frontier orbitals were located along the C4-C5 π bond, particularly the LUMO was split between C4 and C5, predicting the action of enzymes at C5 yielding to 5α and 5β-reduced androgens. Electrostatic potentials might be also of biological importance since they are coincidental with the dipole-moment orientation. Finally, it is interesting that the solvatedlike conformer, its properties, and the OH group laid between the same group of T1 and T2 and with a total energy between the crystals and the gas phase or in vacuo conditions. This results might also explain the biology of testosterone and use them to model the hormone-receptor interaction. © 1997 John Wiley & Sons, Inc.
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  • 16
    Electronic Resource
    Electronic Resource
    A study of methanetetraol dehydration to carbonic acid (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 315-322 
    Details
    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: Two alternative dehydration reactions C(OH)4 → (HO)2CO + H2O and C(OH)4 + H2O → (HO)2CO + 2H2O are studied by ab initio Becke3LYP/6-311 + G** and MP2/6-31G** methods. Calculated energy and geometry characteristics of intermediates and transition states predict a catalytic effect of one water molecule and the exothermism of the transformations. Relevant HF/6-311 + G**, HF/6-31G**, HF/6-31G, and HF/3-21G calculations were performed for comparison. © 1997 John Wiley & Sons, Inc.
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  • 17
    Electronic Resource
    Electronic Resource
    Hydrogen-bonding effects, electrostatic potential, and the antitumor activity of flavone acetic acid and related compounds. III. Ab initio studies on the conformation space (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 97-113 
    Details
    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: Restricted geometry optimizations at the ab initio SCF level with the 3-21G basis set were employed to investigate the conformation space of flavone acetic acid (FAA) and its related compounds. All the conformations are produced from a conformation which is, according to our previous work, probably the active conformation in terms of antitumor activity shown by these compounds. Detailed studies on FAA were carried out while only brief discussions are made on the analogs. The main results obtained are that (1) FAA is a very flexible molecule, e.g., with the energy barrier up to about 3 kcal mol-1 from the reference conformation, the important torsional angle τ1 can change from 27.0° to 117.0°, τ2 from -168.0° to 2.0°, and τ3 from -50.0° to 30.0°; (2) the hydrogen-bonding effect plays an important role in determining lower-energy conformations; (3) among all the FAA conformations considered, some are active and some are inactive; (4) it seems that the analogs will have similar behavior to FAA when the torsional angle τ3 is restricted to the values which are around the equilibrium values; and (5) the hypothesis put forward previously has been further developed in this work. Now, we postulate that efficient charge transfers will lower the energy and that proper charge transfers will activate the molecule. There are mainly two different types of charge transfer corresponding to two different types of conformation, which are specified in this article. © 1997 John Wiley & Sons, Inc.
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  • 18
    Electronic Resource
    Electronic Resource
    Modeling properties of the HF dimer in argon clusters (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 55-65 
    Details
    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 compare geometry configurations, vibrational properties, and electronic structures of (HF)2 in a free state and inside argon atom shells Arn. For the first stage, molecular dynamics calculations for the (HF)2 · Ar62 heterocluster are performed with the help of model potentials HF(SINGLE BOND)HF, Ar(SINGLE BOND)Ar, and Ar(SINGLE BOND)HF. Then, ab initio quantum chemistry analysis is carried out for the smaller systems (HF)2 · Ar15 and (HF)2 · Ar6 when keeping the argon atoms closest to the trapped dimer. We conclude that the hydrogen-bonded complex (HF)2 gains some extra stability inside the argon shells, originating primarily from a decrease of intermolecular distance RFF. Electronic structure calculations are in accord with the changes in dynamical properties, namely, a noticeable increase in the vibrational frequency assigned to the F(SINGLE BOND)F stretching mode (+25 cm-1) and decrease in rms deviations for the corresponding coordinate δFF. In addition to these changes, the argon atoms of the nearest solvent shell donate a small fraction of electron charge which is spent for an increase of population of the antibonding orbital σ*Hf(SINGLE BOND)Ff of the free monomer unit and shift orbital energies primarily of the lone-pair fluorine species. These shifts are greater than the changes due to geometry alterations and the possible inaccuracies of the calculation scheme. © 1997 John Wiley & Sons, Inc.
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  • 19
    Electronic Resource
    Electronic Resource
    Numerical solution for the ground-state energy of the anisotropic Heisenberg model (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 13-21 
    Details
    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 analysis of the anisotropic Heisenberg model is carried out by solving the Bethe ansatz solution of the model numerically as a function of the anisotropy parameter for finite N. A brief introduction to the limit of the infinite chain is presented. The energy for a few special limiting cases of the anisotropy parameter in the Hamiltonian are worked out. Numerical results for finite cycles as well as for the infinite chain are given. Comparison can then be made with the case of finite increasing N. © 1997 John Wiley & Sons, Inc.
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  • 20
    Electronic Resource
    Electronic Resource
    Evaluation of a characteristic atomic radius by an ab initio method (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 47-53 
    Details
    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 MELD program is employed to evaluate the Slater average potential v(r) felt by an electron at the point r within an atom. The characteristic radius R of the atom is then defined by the classical turning point equation v(R) = -I, where I denotes the first ionization potential of the atom. The atomic radii defined in this way have a close correlation with the van der Waals atomic radii. © 1997 John Wiley & Sons, Inc.
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  • 21
    Electronic Resource
    Electronic Resource
    Accurate nonrelativistic energies for 2Pe states of the Li isoelectronic series (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 77-88 
    Details
    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: Highly accurate upper bounds for several 2Pe states of the Li isoelectronic series obtained by extensive Hylleraas-Cl calculations are given. The best value for the 22Pe state (1s2p2) of Li is -5.21373920 au. The evaluation of the occurring integrals is given explicitly. Additionally, we present some expectation values and isotope energies of the Li isoelectronic series. © 1997 John Wiley & Sons, Inc.
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  • 22
    Electronic Resource
    Electronic Resource
    Efficient evaluation of the algebrants of VB wave functions using the successive expansion method. I. Spin S = 0, ½ (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 245-259 
    Details
    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 efficient expansion method for the evaluation of VB matrix elements is introduced. The overlaps of VB wave functions of N electrons can be treated as algebrants, i.e., generalized determinants, of N × N matrices. An algebrant can be expanded with subalgebrants of lower orders in a successive way. By choosing Rumer spin bases and appropriately arranging the expansion, it is found that the number of unique subalgebrants involved in the expansion increases in a quite moderate way with N. In contrast to the traditional symmetric group approach, which explicitly utilizes all N! representation matrices, the new strategy incorporates the group theoretical factors in a simple way in the successive expansion. As only the unique subalgebrants are further expanded, the computational effort required by the new strategy scales in a very acceptable manner with the increasing number of electrons. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 62: 245-259, 1997
    Additional Material: 5 Tab.
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  • 23
    Electronic Resource
    Electronic Resource
    Characters of two-row representations of the symmetric group (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 261-264 
    Details
    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: Characters of irreducible representations (irreps) of the symmetric group corresponding to the two-row Young diagrams, i.e., describing transformation properties of N-electron eigenfunctions of the total spin operators, have been expressed as explicit functions of the number of electrons N and of the total spin quantum number S. The formulas are useful in various areas of theory of many-electron systems, particularly in designing algorithms for evaluation of spectral density moments. © 1997 John Wiley & Sons, Inc.
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  • 24
    Electronic Resource
    Electronic Resource
    Computation of bond dissociation energy for sulfides and disulfides with ab initio and density functional theory methods (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 291-296 
    Details
    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 and S-H, S-S, and S-C bond dissociation energies for hydrogen sulfide, hydrogen disulfide, methanethiol, dimethyl disulfide, and dimethyl disulfide were calculated with both ab initio (ROHF and MP2), hybrid (BHandH, BHandHLYP, Becke3LYP and Becke3P86), and nonlocal (BLYP and BP86) density functional theory (DFT) methods. In all studies the 6-31 + G(d) basis set is used. The computed results are compared to the experimentally obtained values, targeting the selection of a suitable ab initio or DFT method for the study of these systems. © 1997 John Wiley & Sons, Inc.
    Additional Material: 7 Tab.
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  • 25
    Electronic Resource
    Electronic Resource
    Theoretical study on the pyrolysis mechanism and kinetics of β-hydroxyketones (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 297-302 
    Details
    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 mechanism and kinetics for the decomposition of β-hydroxypropaldehyde, primary and secondary β-hydroxyketones, were studied by using ab initio RHF/6-31G and RHF/6-31G* methods. The activation barriers of these reactions were refined to be 39.57, 40.10, and 36.80 kcal mol-1 at the MP2/ /RHF/6-31G* level, respectively. The calculated results show that each decomposition is a concerted process with hydrogen transferring and bond breaking via a six-membered cyclic transition state. The thermal rate constants of the decomposition of primary and secondary β-hydroxyketones were obtained by calculating microcanonical probability fluxes through each transition state. It is theoretically confirmed that methyl substitution at the hydroxyl carbon of β-hydroxyketones causes a small enhancement in rates. The theoretical investigations of the mechanism and the rate constants are in agreement with the experimental results. © 1997 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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  • 26
    Electronic Resource
    Electronic Resource
    Power series with rational coefficients for two-electron atom energies (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 63 (1997), S. 1079-1089 
    Details
    ISSN: 0020-7608
    Keywords: large-order perturbation theory ; lie algebra ; three-body problem ; symbolic computations ; helium atom ; 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 o(4, 2) operator replacements is generalized. As a result, the series whose limiting values when the variable goes to  +∞ should correspond to the two-electron atom energies now have rational coefficients. This generalization allows one also to compute the series for the case of singlet S symmetry, a case which could not be considered in the previous original formulation of the method. Series with rational coefficients for the helium singlet and triplet S ground-state energy are calculated up to order 41 and 45, respectively. Moreover, symbolic computations also allow one to give the first few coefficients of these series for arbitrary values of the nuclear charge Z. Finally, a new method for analytic continuation to the limit  +∞ is presented for the energies of the helium singlet and triplet ground states.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 1079-1089, 1997
    Additional Material: 3 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    A study of bond-cleavage and bond-formation processes in some simple metathesis reactions (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 63 (1997), S. 1099-1106 
    Details
    ISSN: 0020-7608
    Keywords: metathesis reactions ; bond order ; free valence ; minimum energy path ; nonsynchronization ; Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A few simple atom-transfer reactions (i.e., Ȧ+X-A→A-X+Ȧ) are studied by quantum mechanical ab initio methods. Emphasis is given to the detailed analysis of density matrices rather than to the energetics. Results reveal that during these reactions a small free valence always develops on the migrating atom at the transition state. The barriers in these reactions arise from the greater extent of bond cleavage in the reactant than that of bond formation in the transition state. Analysis of bond orders estimated from bond lengths using Pauling's relation also leads to the fact that the bond-cleavage process is more advanced than is the bond-formation process in these reactions.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 1099-1106, 1997
    Additional Material: 4 Ill.
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  • 28
    Electronic Resource
    Electronic Resource
    Electronic absorption and emission spectra of nucleic acids and their components: Some questions of theory and experimentPresented at the International Conference on Quantum Chemistry, Biology, and Pharmacology held at Kiev, U.S.S.R., September 1978. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 307-320 
    Details
    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 results of calculations of the transition energies and polarization in nucleotide bases performed by the CNDO/S CI method are compared with experimental data for long-wavelength and vacuumabsorption bands. The calculations and the analysis of experimental data testify to the existence of n - π* transitions in the first absorption bands of the bases. The study of double-stranded polynucleotides and DNA hypochromism based on the theoretical electronic characteristics of the bases and perturbation theory is performed. The role of stacking and complementary interactions within the hypochromic effect is cleared up. Two mechanisms for the shift of the fluorescence band maximum are investigated: two-proton transfer along H bonds and excimer formation. The study of H-bond potential curves shows the disadvantage of two-proton phototautomerism in the nucleotide base pairs in contrast to model systems. The possibility of excimer state formation in stacked homo- and heterodimers of nucleotide bases is shown within the extended-Hückel treatment. The nature of excimer minimum for the excited-state potential curve is analyzed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560170214
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  • 29
    Electronic Resource
    Electronic Resource
    Equations de Hartree-Fock dependant du temps (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 531-547 
    Details
    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 Hartree-Fock (TDHF) equations are derived up to the second order when the system is perturbed by a monochromatic plane wave. The solutions of the equations are subjected to the orthonormalization conditions satisfied by the orbitals. In the equations, these conditions are expressed by the appearing of coefficients λjkn,ε playing the part of Lagrangian multipliers. Relations between the coefficients λjkn,ε are established. These relations are equivalent to the above-mentioned orthonormalization conditions. This equivalence enables us to substitute for the solution of an integrodifferential equation system subject to constraint conditions, that of a free system. The TDHF equations obtained determine the first- and second-order orbital perturbations, which no doubt verify the orthonormalization conditions. These orbitals can be used in the calculation, up to second order, of different nonlinear optical effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170313
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  • 30
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    Electronic Resource
    Books Received (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 596-596 
    Details
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170317
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  • 31
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    Electronic Resource
    Study of pair correlation in three-electron atoms (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 619-629 
    Details
    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: Pair correlation in the ground state of the Li isoelectronic sequence is studied through four approximate wave functions which incorporate inter- and intrashell pair correlation. Of these functions, two possess symmetry appropriate to a three-electron system, while two do not. The functions are not variational functions in the usual sense. They are instead fixed linear combinations of products of orbitals and pair functions for the appropriate states of two-electron atoms. They are considered here as zero-order approximations to the exact wave functions, and the corresponding zero-order Hamiltonians are obtained. The simplest of these functions is improved by the introduction of a screening parameter for the “outer” electron. This latter function is found to be a satisfactory compromise between accuracy and simplicity and is proposed for study via higher-order perturbation theory.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170404
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  • 32
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    π-Orbital electron-energy contributions to chemical reaction heats, I. Reactions involving only linear molecules containing up to three first-row atoms (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 599-608 
    Details
    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 calculations of various expectation energies have been made for the reactant and product species in six reactions that involve only small linear molecules. The reactions include fission by hydrogen, addition of hydrogen, exchange of triply bonded atoms, fluorination, and oxygen atom transfer. The change in total electronic energy is not invariably the result of changes in inner shell energy and outer shell σ- and π-electron energies simply augmenting each other, but in several cases there is a complex interplay of opposing effects. This approach gives a different insight into the energetic aspects of changes in bonding from that derived from the concept of shared electron pairs in σ and π bonds together with lone pairs in valence shells. Changes in π-electron energy are shown to be important in a reaction in which neither reactant nor product molecules contain π bonds in the usual chemical sense. While in a reaction in which there is a complete change in the nature of the triple bonds, and hence the π bonding, the change in π-electron energy makes a smaller contribution than either the change in inner shell or the outer shell σ-electron energies.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170402
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  • 33
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    Calculation of molecular electric polarizabilities and dipole moments. III. BH moleculeResearch was supported by the National Science Foundation under Grant No. CHE 77-22638. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 479-483 
    Details
    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 use a previously proposed variation-perturbation method to calculate the electric polarizabilities and the electric dipole moment at equilibrium nuclear distance of the BH molecule. We obtain 3.56 × 10-24 cm3 for the perpendicular polarizability αxx and 3.22 × 10-24 cm3 for the parallel polarizability αzz. Our result for the electric dipole moment μ0 is 1.734 debye units; there is no reliable experimental result to compare it with.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170309
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    Resonance energy of very large benzenoid hydrocarbonsThis paper is dedicated to Professor Linus Pauling. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 549-586 
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    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 resonance energy of conjugated benzenoid systems is expressed as contributions arising from independent conjugated circuits. The scheme has been applied to numerous very large conjugated systems. In many cases, it was possible to find regularities in the increments for the resonance energy within a family of benzenoid systems as the number of benzene rings is increased.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170314
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    Electronic Resource
    Dielectric and electronic properties of biological materials. R. Pethig. John Wiley & Sons, New York, 1979. 376 pp. Price: $15.00 (cloth) (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 595-595 
    Details
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170316
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  • 36
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    Further analysis of the iterative hypervirial-scaling method (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 609-618 
    Details
    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 previously given iterative procedure to improve wave functions is analyzed. Its relationship with other well-known approximation methods is investigated. Hypervirial operators depending on a real parameter are proposed and their connection with the employment of an infinite number of hypervirial relations is analyzed. A way to use formulas that are valid for exact eigenfunctions in the case of approximate functions is presented. Formal results are applied to the harmonic oscillator and hydrogen atom models in order to show their practical utilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170403
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  • 37
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    Active-site α-helix in papain and the stability of the ion pair RS- ··· ImH+. Ab initio molecular orbital study (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 651-671 
    Details
    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 MO calculations, using both minimal (STO-3G) and extended (Roos-Siegbahn) basis sets are reported for the systems methanethiol-imidazole, methanethiol-imidazole-formaldehyde, and methanethiol-imidazole-formamide, which, together with a point-change representation of a long α-helix, form models for the active site of papain. It is shown that the large electric field exerted by the helix in the active-site region is responsible for the presence of the essential residues Cys 25 and His 159 in the form of an ion pair RS- ··· ImH+, which is crucial for a recently proposed mechanism for the catalytic action of the enzyme. Also, an explanation is given for the anomalies in measured pK values for these residues. Detailed studies on the (sub)systems show that minimal basis sets lack the flexibility necessary for describing the type of proton transfer involved. We conclude that α-helices are essential parts of enzymes and that they play a significant role in the catalytic process.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170407
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  • 38
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    Electronic Resource
    Possible generalization of the optimized diatomics-in molecules theory: Further studies of the diatomic state mixing parameter adjustment (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 679-687 
    Details
    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 generalization of optimized diatomics-in-molecules method that provides an accurate treatment of overlap integrals is presented. The possibilities of the method to reproduce potential surfaces of the 4B2, 2B2, and 2A1 states of the H3 molecule are investigated. It is shown that satisfactory results can be achieved only for a single state under consideration, but not for the three states simultaneously.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170409
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  • 39
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    Electronic Resource
    Ab initio calculation of ESCA satellite intensities for a copper-chlorine complex (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 719-724 
    Details
    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 calculations carried out on the planar cluster CuCl42- suggest that the strong satellites at the high-binding energy side of inner-shell ESCA lines of Cu are due to charge relaxations in the σ-bonding orbitals which mix with Cu 3d. The satellite state with the largest intensity may be described as a one-electron excitation Cu 3d → Cl 3p.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170412
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  • 40
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    Pairwise correlated generalized valence bond model of electronic structure. VII. The b 3∑u+ state of H2 (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 975-982 
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    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 modification of the overlap approximation for triplet pair correlation energies is presented. The modification allows the use of either the canonical absolute overlap or the minimum absolute overlap. When applied to the b 3∑u+ state of H2, this approximation reproduces the observed correlation energy to within 0.0002 hartree (or ±3%) for all internuclear distances from 1.3 bohr to infinity.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170512
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  • 41
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    Zeroes of the quartic oscillator eigenfunctions (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1039-1041 
    Details
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170517
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  • 42
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    Atomic and molecular collision theory (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1042-1042 
    Details
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170518
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  • 43
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    Nonadditivity of the SCF interaction energy in the (LiH)3 complex (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1069-1074 
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    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
    Description / Table of Contents: Le rǒle de la nonadditivité pour l'énergie d'interaction entre trois molécules de LiH a été examiné dans le cadre de la méthode ab-initio-SCF. La partie nonadditive de l'énergie d'interaction est plus importante pour une structure cyclique que pour un trimère linéaire; elle est stabilisante dans les deux cas. La valeur du rapport entre les termes à deux et à trois corps pour des points différents sur l'hypersurface de l'énergie est discutée.
    Abstract: Die Bedeutung der Nichtadditivität in der Wechselwirkungsenergie zwischen drei LiH-Molekülen ist im Rahmen des ab-initio-SCF-Verfahrens untersucht worden. Der nichtadditive Teil der Wechselwirkungsenergie ist wichtiger für eine zyklische Struktur als in einem linearen Trimer; er ist in beiden Fallen stabilisierend. Das Verhältnis zwischen Zwei- und Dreikörperglieder für verschiedene Punkte auf der Energiehyperfläche wird diskutiert.
    Notes: The role of nonadditivity of the interaction energy between three LiH molecules was investigated within the SCF ab initio framework. The nonadditive part of the interaction energy is more important in the case of a cyclic structure than in a linear trimer, and is stabilizing in both cases. The value of the ratio of three-body and two-body terms for different points on the energy hypersurface is discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170604
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  • 44
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    Electronic Resource
    Gaussian expansions of hydrogenic functions involving few variational parameters (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1099-1109 
    Details
    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
    Description / Table of Contents: Des développments gaussiens complètement optimisés des fonctions hydrogénoïdes de type 1s, 2pz, 3dxy, et 4fxyz ont été pratiquement reproduits par une construction spéciale des paramètres variationnels. L'utilité des fonctions génératrices utilisées est discutée brièvement.
    Abstract: Vollständig optimisierte Gaussentwicklungen wasserstoffähnlicher Funktionen von Typ 1s, 2pz, 3dxy, und 4fxyz sind mittels eines speziellen Verfahrens für die bestimmung der Variationsparameter praktisch reproduziert worden. Der Nutzen der angewandten erzeugenden Funktionen wird kurz diskutiert.
    Notes: Fully optimized lengthy Gaussian expansions of hydrogenic 1s and 2pz functions have been practically reproduced by generating the variational parameters by means of suitably chosen functions involving only few parameters. Hydrogenic 3dxy and 4fxyz functions have been approximated in a similar way. The usefulness of such generating functions is briefly discussed.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170606
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  • 45
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    New method for approximate Hartree-Fock calculations using density approximations and coulomb field corrections. II (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1125-1141 
    Details
    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
    Description / Table of Contents: L'approximation HF présentée dans la partie I a été testée par rapport à plusieurs propriétés moléculaires. Trois niveaux d'aproximation différents a, b, et c sont considérés. Des résultats satisfaisants - en comparaison avec des calculs HF “exacts” - sont obtenus avec la base STO-3G et le niveau a. A ce niveau-ci l'erreur dans l'énergie de liaison est de 0.001-0.025 a.u. pour toutes les molécules considérées, qui contiennent jusqu'à six atomes de la première ligne comme par exemple le cyclopentanone (C5OH8). L'erreur dans les énergies de réaction traitées ici est d'environ 4 kcal/mol (l'erreur maximale est de 9 kcal/mol). Les énergies orbitalaires, les moments dipolaires, les charges brutes, les géométries d'équilibres et les barrières de rotation interne sont bien reproduits par notre méthode à tous les trois niveaux.
    Abstract: Die HF-Näherungsmethode, welche im Teil I vorgestellt wurde, wird an einigen Moleküleigenschaften getestet. Drei Näherungsstufen a, b, und c werden untersucht. Zufriedenstellende Ergebnisse - verglichen mit entsprechenden “exakten” HF-Rechnungen - erhält man mit der STO-3G Basis und der Näherungsstufe a. Bei dieser Näherung ist der Fehler in der Bindungsenergie 0.001-0.025 a.u. für alle untersuchten Moleküle, welche bis zu 6 Atome der 1. Reihe enthalten, wie z.B. Cyclopentanon (C5OH8). Der Fehler in den hier behandelten Reaktionsenergien beträgt etwa 4 kcal/mol (der maximale Fehler beträgt 9 kcal/mol). Orbitalenergien, Diplolmomente, Bruttoladungen, Gleichgewichtsgeometrien und Rotationsbarrieren werden durch die Näherungsmethode bei allen Näherungsstufen gut wiedergegeben.
    Notes: The HF approximation method that was outlined in Paper I is tested with respect to several molecular properties. Three different levels of approximation a, b, and c are considered. Satisfactory results - compared to corresponding “exact” HF calculations - are obtained with the STO-3G basis and the approximation level a. At this level the error in the binding energy is 0.001-0.025 a.u. for all considered molecules which contain up to six first-row atoms as, e.g., cyclopentanone (C5OH8). The error in the reaction energies considered here is about 4 kcal/mol (the maximal error is 9 kcal/mol). Orbital energies, dipole moments, gross charges, equilibrium geometries, and barriers to internal rotation are well reproduced by the approximation method at all three levels.
    Additional Material: 5 Ill.
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    Effect of side-chain disorder on the electronic structure of proteins (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 995-1006 
    Details
    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 influence of side-chain disorder on the electronic structure of proteins has been investigated in the case of polypeptides containing two or three different amino acid residues. It has been found that due to the different potentials of different side-chain groups, the original valence and conduction bands of the homopolypeptides are split into narrow bands. The comparison of the densities of electronic states in simple homopolypeptides and in composite polymers shows that new forbidden regions in the energy spectrum of proteins may develop. The consequences of these effects for the semiconductive properties of proteins are discussed.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560170514
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    Improvement of an integral approximation scheme based on semiorthogonalized orbitals (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1031-1037 
    Details
    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 a previous paper, a scheme of integral approximation was proposed, in which a large number of two-electron integrals containing a certain kind of orbital pairs, i.e., weakly related pairs, can be neglected. A new criterion for partitioning orbital pairs into two groups, i.e., strongly and weakly related pairs, is introduced in order to allow for neglect of more integrals without sacrificing the accuracy of a computation. Test calculations on the BH3—C2H4 complex show that by the use of the new version, results of roughly the same accuracy as was obtained by the old version is obtained by retaining 80% of the integrals used in the old version. This kind of saving is more significant for larger molecules. For example, in a calculation on Cu-porphine with 203 CGTO'S, the revised version will require about 2.0 × 106 integrals, while the original version will require about 4.5 × 106. And these two approximate calculations are expected to give the results of roughly the same accuracy.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560170516
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    Biological effects of magnetic fields and cooperative phenomenaThis paper was presented at the Sixth International Symposium on Quantum Biology and Quantum Pharmacology held at Flagler Beach, FL, March 4-10, 1979. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1043-1046 
    Details
    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: Cooperative phenomena may be involved in the biological effects of magnetic fields (H), since its effects on isolated atoms or ions, at room temperature, are very weak. It is suggested that interactions at the social level can considerably increase the efficiency of H in orienting the displacements of animals. This effect is discussed with a simple mathematical model inspired on superparamagnetism. In case of very weak interactions of H with isolated animals, it suggests that orientation could only be made visible through cooperativity at the social level. These results are generalized to other physical stimuli and effects, leading to the concept of cooperative sensory response, i.e., a group response to an external physical agent even when its effect on isolated members of the group is undetectable.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560170602
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    Ab initio calculations on large molecules using molecular fragments. Generalization of the molecular fragment basis at the minimum basis set levelSupported in part by the Division of Basic Energy Sciences of the United States Department of Energy, and the Upjohn Company, Kalamazoo, Michigan. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1075-1097 
    Details
    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
    Description / Table of Contents: En déterminant les paramètres des jeux de base dans des environnements moléculaires par d'autres critères que l'énergie totale, il est démontré qu'une généralisation de la base pour des fragments moléculaires peut ětre obtenue, dans laquelle les propriétés géométriques et celles de la structure électronique sont prédites considérablement mieux qu'avec des bases de taille semblable. Comme premier pas dans le développement d'une série de bases avec une flexibilité et une précision de plus en plus prononcée, on a construit plusieurs jeux de base de type simple zéta avec une contraction gaussienne pour chaque orbitale de base. Les meilleures de ces bases donnent des propriétés géométriques et électroniques pour une série de molécules organiques avec'une précision meilleure que celle obtenue par la base correspondante de type STO-2G et semblable dans la plupart des cas à STO-3G. En outre cette base peut ětre utilisée soit avec des gaussiennes cartésiennes, soit avec des gaussiennes sphériques flottantes.
    Abstract: Durch eine Bestimmung von Basissatzparametern in Molekülumgebungen mit anderen Kriterien als der Gesamtenergie wird gezeigt, dass eine Verallgemeinerung des Molekülfragmentsbasissatzes erhalten werden kann, mit welchem geometrischen und Elektronstruktureigenschaften beträchtlich besser als mit anderen Basissätzen ähnlicher Grösse vorhergesagt werden können. Als erster Schritt in der Entwicklung einer Reihe von Basissätzen mit sukzessiv grösserer Flexibilität und Genauigkeit werden mehrere Basissätze von Einzelzetatyp durch eine Gauss'sche Kontraktion für jedes Basisorbital konstruiert. Mit den besten dieser Basissätze werden geometrische und elektronische Eigen-schaften für eine Reihe von organischen Molekülen mit besserer Genauigkeit als dem entsprechenden STO-2G Basissatz und in vielen Fallen ähnlich dem STO-2G Satz erhalten. Weiter wird gezeiget, dass dieser Basissatz mit sowohl Cartesischen als fliesseden sphärischen Gaussfunktionen vereinbar ist.
    Notes: By determining basis set parameters in molecular environments using other criteria than total energy, it is shown that a generalization of the molecular fragment basis can be obtained in which calculated geometric and electronic structural properties are predicted substantially better than with other basis sets of similar size. As a first step in the development of a series of basis sets having successively greater flexibility and accuracy, several single-zeta basis sets are created, using a two-Gaussian contraction for each basis orbital. The best of these basis sets produced calculated geometric and electronic properties for a series of molecules that model a wide variety of organic molecules that are of better accuracy than the corresponding STO-2G basis, and similar in most cases to STO-3G. In addition, the basis set is shown to be applicable in either a Cartesian Gaussian basis or a floating spherical Gaussian basis.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560170605
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    New method for approximate Hartree-Fock calculations using density approximations and coulomb field corrections. I (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1111-1123 
    Details
    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
    Description / Table of Contents: Une méthode est proposée, qui réduit considérablement le travail numérique dans un calcul HF en réduisant le nombre d'intégrales à deux électrons qui doivent ětre calculées. Les procédés suivants sont utilisés: (i) la densité électronique est approximée par un petit nombre de fonctions pour la partie de Coulomb de la matrice HF; (ii) cette densité approchée est modifiée pour améliorer son potentiel; (iii) dans la partie d'échange une fonction de base χ est remplacée par une fonction \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \chi $\end{document} avec un nombre moindre de lobes gaussines; (iv) l'érreur causée par ce remplacement-ci est réduite par une modification des densités \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \chi _i \tilde \chi _j $\end{document} dans les intégrales d'échange. Le temps de calcul pour les intégrales est réduit par un facteur 6 pour des molécules contenant cinq atomes de la première ligne comme par exemple CF4, si l'on utilise une base 7S/3P contractée à (5, 1, 1/3). Le temps augmente approximativement avec n3, si n est le nombre de lobes gaussiens.
    Abstract: Eine Methode wird vorgeschlagen, welche den numerischen Aufwand von Hartree-Foch Rechnungen dadurch verringert, indem die Zahl der zu berechnenden Zweielektronenintegrale reduziert wird. Dabei werden folgende Konzepte verwendet: (i) Zur Berechnung des Coulombanteils der HF Matrix wird die Elektronendichte durch wenig Funktionen approximiert. (ii) Die approximierte Dichte wird so modifiziert, daß ihr Potential verbessert wird. (iii) Zur Berechnung des Austauschanteils wird eine Basisfunktion χ durch eine Funktion \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \chi $\end{document} ersetzt, welche weniger Gauss-lobes enthält. (iv) Der dadurch hervorgerufene Fehler wird durch eine Änderung der in den Austauschintegralen vorkommenden Dichten \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \chi _i \tilde \chi _j $\end{document} reduziert. Für Moleküle, welche 5 Atome der 1. Reihe enthalten, wie z.B. CF4, wird die Rechenzeit für den Integralteil um den Faktor 6 reduziert, wenn eine 7S/3P Basis kontrahiert zu (5, 1, 1/3) verwendet wird. Die Integralzeit nimmt etwa mit der 3. Potenz der Zahl der Gauss-lobes zu.
    Notes: A method is proposed that reduces the computational effort of HF calculations considerably by reducing the number of two-electron integrals that have to be calculated. The following concepts are used: (i) approximation of the electron density by only few functions for the Coulomb part of the HF matrix; (ii) modification of this approximate density, to improve its Coulomb field; (iii) in the exchange part, a basis function χ is replaced by a function \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \chi $\end{document} consisting of fewer Gaussian lobes; (iv) the error caused by this replacement is reduced by a modification of the densities \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \chi _i \tilde \chi _j $\end{document} in the exchange integrals. The computation time of the integral part is reduced by a factor 6 for molecules containing five first-row atoms as, e.g., CF4, if one uses a 7S/3P basis set contracted to (5, 1, 1/3). The integral time increases roughly with n3, if n is the number of Gaussian lobes.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/qua.560170607
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    Masthead (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980) 
    Details
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180101
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    New derivation and a k-particle generalization of SCF-type theories (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 3-9 
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    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 hierarchy of necessary conditions that an exact density matrix of a pure state or an ensemble has to satisfy is derived, namely the hermiticity of certain operators F(k). For k = 1 this reduces to the well-known Hartree-Fock condition. It is then shown that the kth set of conditions is equivalent to stationarity of the energy with respect to unitary k-particle transformations. k-Particle generalizations of Hartree-Fock theory are then discussed both in the spirit of k-particle pseudoeigenvalue equations and in the framework of a Newton-Raphson-type constructive scheme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180103
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    Binding energies at different momenta for the valence orbitals of HCl by the binary (e, 2e) method (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 275-280 
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    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 binding energy spectra for the valence orbitals of hydrogen chloride have been obtained using the binary (e,2e) method at 1200 eV. The strength of the innermost valence orbital (4σ) is severely split among several ion states in the energy range 25 to 41 eV. The measured cross sections are compared with results of calculations using contracted Gaussian basis sets of double-zeta quality, and with a one-particle Green's function calculation.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560180138
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    Comparison between intervalence charge transfer and molecular tautomerism (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 307-310 
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    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 charge exchange process in the intervalence (mixed-valence) system is interpreted in terms of the nonstationary state mechanism which is a well-known approach for rationalizing the molecular tautomerism process. The two kinds of processes are viewed in a close analogy in the sense that both involve a pair of near-degenerate levels in a double-well potential. However, a comparison is made between the two cases to demonstrate that an electron moves not only faster but also farther in distance than a nucleus does.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560180143
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    Vibrational spectra of molecules in the Hartree-Fock dielectric screening approachWork supported by a research grant from the Sponsored Research Committee of Control Data Corporation, Minneapolis, Minnesota. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 311-315 
    Details
    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: Traditionally, the calculation of the vibrational spectra of molecules involves at one point or another a numerical differentiation procedure. Such a method has some serious drawbacks both in efficiency and in accuracy. In this paper, an alternative method based on linear response theory is presented. The second derivative of the ground-state energy is expressed in terms of the electron density response matrix by means of perturbation theory. The unperturbed wave functions are obtained from the Hartree-Fock equation. First-order perturbation theory applied to this equation leads to the Hartree-Fock linear response. As an illustration of this method the vibrational frequency of a H2 molecule is calculated. The result is 1.348 × 1014 Hz as compared to the experimental value of 1.319 × 1014 Hz. This method is also applicable in the calculation of the phonon dispersion curves of solids.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/qua.560180144
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    QCLDB - Quantum chemistry literature data base - a trial (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 393-396 
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    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 brief account of a quantum chemistry literature data base (QCLDB) is described, which contains the key information of about 2000 papers of ab initio calculations of atoms and molecules published in 1977-1979. The QCLDB is stored in a computer and can be sorted and rearranged into author and substance indices. Selection of the items for each paper in a computer-readable data base is discussed.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/qua.560180208
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    Metal bridge effectPart V in the Series “Quantum chemical aspects of some problems in bioinorganic chemistry,” see Refs. 1, 6-8.: V. Quantum chemical studies of some metal chelates (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 409-419 
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    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: Metal chelates [(C2H2X2)2M]n with ligating atoms X = NH, O, S and central atoms M = Be2+, Mg2+, Ni2+, Zn2+ (n = 0, ± 2), and M = Li+, Cu+ (n = ± 1, -3), have been studied in our Laboratory for some years by ab initio calculations. In this article it is shown that certain features of the complexes are the same for all the different metals in our series. These features include a drastic reduction of the energy gap between unoccupied and occupied orbitals, when electrons are added to the positively charged complexes. This change of the energy gap is shown to be an effect of the ligand dimer [(C2H2X2)2]n. But this dimer can only exist when a positive ion, e.g., a metal ion, forms a bridge between the two monomers. The reduced energy gap implies a strong bathochromic shift of the electronic spectrum and low electrical resistivity.
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    MO Study of the photochemical behavior of the imine bond (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 457-462 
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    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 photoisomerization of imine compounds is studied in terms of an ab initio MO CI calculation. The potential curves of the syn-anti isomerization via the rotation and the inversion are examined for benzaldimine. It is suggested that the photoisomerization is initiated through the rotation around the C—N bond in both singlet and triplet states. The ease of the photoisomerization is found to be determined by both the conformation of phenyl ring in the ground state and the energy difference of vertically excited states between two isomers.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560180215
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    Mechanism of binding of iron to potential therapeutic chelating agents (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 493-500 
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    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: To aid in designing new therapeutic iron chelating agents, the mechanism of iron binding to prototypic heterocyclic carboxaldehyde thiosemicarbazones has been studied. Based on molecular orbital and spectroscopic studies, iron (II) is found to bind in a covalent manner, while iron(III) seems to interact ionically. However, with both iron(II) and iron(III), chelate formation is dependent on charge interaction between the metal and the coordinating atoms of the ligand.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560180219
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    β--Decay effect on the proton movement in the pyridine-pyrrole hydrogen-bonded system (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 515-519 
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    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 potential-energy curves for the movement of proton along the hydrogen-bond direction were calculated for the parent and cations produced from the β- decay of pyridine-pyrrole labeled by tritium (3H) or carbon-14(14C). For all cations the double minimum potential is predicted to be formed, and the activation energy for the proton transfer from one well to the other is about 10.0 kcal/mol, which is much lower than that in the (NH2—H—NH2)+ ion. A positional effect of nuclear transformation is scarcely expected in 3H β- decay, whereas a slight positional effect may be expected in 14C β- decay.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560180222
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    Infrared absorption of nonpolar molecules in rattling motion (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 533-537 
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    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 study has been made on the translational or “rattling” motion of homonuclear diatomic molecules encaged in β-quinol clathrates. By the use of an adjustable parameter for the van der Waals radius, experimental results have been explained fairly well.
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    URL: http://dx.doi.org/10.1002/qua.560180225
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    Hydrophile-hydrophobe equilibrium of some prostaglandins - CNDO/SW study (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 501-508 
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    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 problem of the existence of a prostaglandin (PG) receptor is still controversial, but it seems to be clear that the main action of the PGs concerns the interface of the cellular membrane (which has a predominantly lipid character) and the extracellular liquid (which mainly consists of water). Also especially in the case of the exogenous PGs, the transport of these substances in the organism in influenced by the hydrophilic-hydrophobic properties of the reactive molecules. These properties can be estimated by MO studies using a solvation model and a semiempirical method of calculation. This paper is concerned with the molecules of PGA1 and PGE1. MO studies were performed for these molecules with the CNDO/SW method in order to calculate ionization potentials, dipole moments, and molecular polarizabilities. With these computed molecular properties, the electrostatic and van der Waals interactions with water and octanol molecules are evaluated and compared within the framework of the original model. This study allows the differentiation of the hydrophilic-hydrophobic character of the PGs investigated and the comparison of the results with experimental data.
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    URL: http://dx.doi.org/10.1002/qua.560180220
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    Explanation of the artifact structure predictions within the semiempirical ZDO SCF supermolecular approach (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 189-191 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180126
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  • 64
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    On the localization of defects (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 607-613 
    Details
    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 range in ordinary space of a defect in a solid, polymer, or a large molecule is an important parameter in many physical and chemical situations like, e.g., substitutional and interstitial impurities in ionic crystals, deep and shallow energy levels in semiconductors, core holes in systems studied by photoelectron spectroscopy, and hydrogen in metals. Both the electronic structure and the lattice of the host molecule or solid are normally influenced by the defect, and it is desirable to treat, as far as possible, these two aspects together. An explicit procedure for investigating the degree of localization is proposed that is based on the direct calculation of Wannier functions and partitioning technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180234
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  • 65
    Electronic Resource
    Electronic Resource
    Exciton transfer in the two-dimensional antiferromagnet (C2H5NH3)2MnCl4 (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 619-623 
    Details
    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: Exciton transfers in the two-dimensional and spin-canted antiferromagnet (C2H5NH3)2MnCl4 were studied by investigating the absorption spectra 6A1g → 4T2g(4D) of Mn2+. A magnon side band (exciton-magnon simultaneous excitation) which has an anomalous shape with the cutoffs at the low-energy as well as the high-energy sides was observed. This anomalous shape could be reproduced in calculation as magnon side band, considering both the intersublattice and intrasublattice exciton transfers. From the analysis of this band shape, the magnitudes of the intersublattice and intrasublattice exciton transfers are estimated to be 10.2 and 6.8 cm-1, respectively. In the case of simple antiferromagnets without spin canting, the intersublattice exciton transfer process is forbidden because of the spin angular momentum. However, in the case of (C2H5NH3)2MnCl4, the prohibition of the intersublattice exciton transfer is removed by the canted-spin arrangement.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180236
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  • 66
    Electronic Resource
    Electronic Resource
    Gaussian matrix elements of the operator X12ρ: Reduction to confluent hypergeometric functions (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 695-708 
    Details
    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 has been proposed for calculating the Gaussian matrix elements of the interaction operator represented by an arbitrary degree of interelectron distance X12ρ. The method is based on the expansion of two-electron integrals as the sum of one-electron integrals which in turn admit compact operator representation in terms of confluent hypergeometric functions. The generating differential operator has been shown to be related to the modified Hermitian polynomials. The standard structure of the special functions encountered in this approach is useful in studying the analytical behavior of the integrals and makes it possible to obtain for these integrals recurrence relations, direct algebraic expressions in the forms of finite sum of confluent hypergeometric functions, integral representations, and asymptotic properties. Unlike the usual methods based on integral transformation of the interaction operator, the proposed approach has a wider field of application, and in addition, leads to compact and convenient analytical expressions. The idea of using differential properties of integrals to simplify the integrand structure gives the proposed approach a certain resemblance to that suggested by Boys but not developed in detail in his pioneer work.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180305
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  • 67
    Electronic Resource
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    Local behavior of hückel parameters (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 775-782 
    Details
    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 Hückel parameters are investigated by using a mapping concept. The mapping is constructed by means of the Linderberg relation. No efforts are made to get a numerically correct description of the Hückel parameters.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180311
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  • 68
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    Evaluation of MINDO/3 calculations in simple amides, ureas, and heterocycles of biological interest (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 797-810 
    Details
    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 performance of the MINDO/3 method has been evaluated in simple heteroatomic molecules that are representative of several important biological systems. Molecular geometries are accurate to within 0.04 Å for bond lengths, and 3° for most bond angles. Dipole moments and charge distributions are estimated satisfactorily, and ionization potentials are predicted to an accuracy of 0.5 eV. The method is less accurate in estimating the ionization of some upper level σ orbitals. The overall evaluation shows that MINDO/3 provides a good description of the geometries and electronic properties of the molecules studied. The results of MINDO/3 calculations in several other chemical systems are also reviewed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180313
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  • 69
    Electronic Resource
    Electronic Resource
    Configuration interaction matrix elements. III. Spin functions relating the unitary and symmetric group approaches (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 841-866 
    Details
    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: Spin functions that are compatible with orbital ordering and geminal antisymmetry conditions are investigated. It is shown that two widely used classes of spin functions, namely, the spin-bonded functions and Yamanouchi-Kotani (or, equivalently, Gelfand-Tsetlin) functions possess these properties. The relationship of the latter with Young-Yamanouchi spin functions is also outlined using graphical techniques of spin algebras. These techniques are also used to rederive the Hamiltonian matrix elements between spin-bonded functions and to show the relationship among the various schemes used in this case.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180317
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  • 70
    Electronic Resource
    Electronic Resource
    Self-consistent approximation to the polarization propagator (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 1109-1131 
    Details
    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 theorem is presented that characterizes approximate states and truncated operator manifolds associated with self-consistent approximate propagators. This theorem establishes a natural relationship between Hermiticity, stationarity, nonredundance and completeness of operator manifolds, model time evolution, and the vacuum condition. For the case of the polarization propagator we describe algorithms by which we can construct states and manifolds that satisfy this theorem and the vacuum condition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180417
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  • 71
    Electronic Resource
    Electronic Resource
    Multiple scattering mass operator method for molecular orbital calculationsWork supported by the Brazilian agencies CNPq and FAPESP. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 1165-1173 
    Details
    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 exchange-correlation potential model to be used in connection with the multiple scattering method is presented. Retaining the main advantages of the multiple scattering method with the Xα potential, particularly its low computational requirements, this new formalism does not require any adjustable parameter. Test calculations on the NiF64- system are reported and compared with experimental and ab initio results.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180505
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  • 72
    Electronic Resource
    Electronic Resource
    Molecular-orbital treatment of complex cations of magnesium and beryllium with acetonitrile (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 1405-1413 
    Details
    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: Semiempirical MO calculations of the self-consistent charge and configuration (SCCC) method are reported for the acetonitrile-metal solvated species (CH3CN)xMn+, where M = Be2+ and Mg2+. Comparison of the delocalization energies for various chemical structures x = 1, 2, 3, 4, 6 leads to an expectation of a tetrahedral structure for the Be2+ species and an octahedral structure for the Mg2+ species. The electronic nature of the donor-acceptor interaction is also discussed.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180606
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  • 73
    Electronic Resource
    Electronic Resource
    Orbital contributions to some two-electron properties (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 1465-1472 
    Details
    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: Analytical formulas are given for the orbital contributions to two-electron properties such as 〈r12n〉, with n = -2, -1, 1, 2, 3, and 4, for atomic systems in which orbitals are expanded as linear combinations of Gaussian functions. Numerical values for all possible contributions in the atoms Li to Ne have been calculated at the Hartree-Fock level. These quantities are compared and discussed to show what kind of information can be obtained from such quantities. The influence of the basis set size has also been considered.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180610
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  • 74
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    Electronic Resource
    Variational function of the Padé type for the ground state of the x4 anharmonic oscillator (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 1485-1487 
    Details
    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: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180614
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  • 75
    Electronic Resource
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    Computer-generated formulas for overlap integrals of slater-type orbitals (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 709-713 
    Details
    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: Using a modified form of Sharma's method for the expansion of a Slater-type orbital in spherical harmonics about a displaced center, a general expression for the overlap integral between two orbitals is derived that is equivalent to that given by Sharma. By use of a simple kind of “computer algebra” this expression is developed here into a formula that is equivalent to earlier known ones and may have computational advantages when the generated formula coefficients are stored. This method is capable of extension to more complicated integrals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180306
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  • 76
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    Electronic Resource
    Role of CA2+ ion in the abortifacient action of prostaglandins. II. Molecular orbital and conformation energy calculations of PGA1 (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 891-904 
    Details
    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: This paper reports some theoretical studies of PGA1 using conformational and molecular orbital techniques. The conformation energy (CE) calculations, using empirical potential-energy functions, for intrinsic torsional rotations around C12—C13 (θ), C7—C8 (Ψ), and C14—C15 (φ) show a number of energy minima. The relative value of the CE for these minima ranges from 4.09 to 8.01 kcal/mol. An additional rotation around C4—C5 (χ) giving “twist” to the carboxyl chains lowers the CE value by 2-3 kcal/mol and a conformation with CE value 2.39 kcal/mol less than crystallographic one is obtained. The interchain interaction energy showed changes with conformations. No significant change in the interchain interaction energy was observed due to “twist” in the carboxyl chain. The isopotential mapping study demonstrated the probable ionic binding site near the carboxyl and the ring (O9) oxygens. Conformational and molecular orbital results are discussed in the light of the reduced abortifacient potency of PGA1 with respect to PGF2α and the possible role of Ca2+ ions in this action.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180319
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  • 77
    Electronic Resource
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    Improved transformation algorithm of two-electron integrals from atomic orbital basis to a symmetry orbital basis (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 1157-1163 
    Details
    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 transformation of two-electron integrals from an atomic orbital basis to a symmetry orbital basis is a straightforward procedure, but becomes a time-consuming process when the system has high symmetry. In the conventional transformation algorithm, the number of multiplications is proportional to the fifth power of the basis size. To reduce the computer time, a new transformation algorithm is proposed. In this method, the number of multiplications for the transformation is proportional to the fourth power of the number of atomic orbitals in an equivalent orbital group. A new transformation program has been completed and tested against the conventional n5 method. The present method may be regarded as extension of Almlöf's method to any molecular point group. The program cuts the CPU time for the transformation to one-third in calculations for C4H8 and NiF6. This reduction is quite significant for large systems having high symmetry.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180504
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  • 78
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    Conformational studies of double-helical polynucleotides by the method of pair-wise potential functionsPrepented at the International Conference on Quantum Chemistry, Biology, and Pharmacology held at Keiv, U.S.S.R., September 1978. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 321-326 
    Details
    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: Double-helical polynucleotide conformations, poly(dA)·poly(dT), poly(d(A-T))·poly(d(T-A))·poly(dG)·poly(dC), and poly(d(G-C))·poly(d(C-G)) are analyzed by the atom-atom potential method. The energy optimization is carried out in the space of eight independent geometric parameters using analytical procedures for the constraints, taking into account the flexibility of the β-D-deoxyribose rings. At the first stage, the full screening of atomic partial charges was assumed. The structures of the calculated B and the A forms of DNA are characterized by low energy and absence of short contacts; the dihedral angles are near the average values in the monomers. With the typical energy difference of 3-5 kcal/mol nucleotide pairs in all cases, the B form is more preferable as compared to the A form. At the final step the effect of the Coulomb term is evaluated for poly(dA)·poly(dT) using various values of the effective dielectric constant (ε = 28, 24, 20, 18, 14, 12, 10, 8, 6, 4, and 1). If ε ≤24, the energy optimization leads A to B. We discuss the stereochemical details of the intermediate conformations on the A-B path and hypothesize the nature of stability of the A and the B forms and the mechanism of the A-B transition.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170215
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  • 79
    Electronic Resource
    Electronic Resource
    Nonadditivity of interaction in water trimers (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 377-398 
    Details
    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 energy of (H2O)3 has been calculated for 29 geometrical configurations of the trimer using the SCF LCAO MO method and extended as well as minimal basis sets of Gaussian functions. For two configurations two intermediate basis sets have also been tested. The results show the nonadditive component of the interaction energy to be small. They also indicate that fairly reliable results for the trimer can be obtained using minimal basis sets and the counterpoise method to eliminate the basis set superposition error. The nonadditive contribution to the interaction energy is shown to be mainly due to the long-range induction interaction.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170302
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  • 80
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    Electronic Resource
    Two useful identities involving spherical harmonics (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 459-465 
    Details
    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 present two identities that permit a simplification of some lengthy derivations with spherical harmonics. Examples of their use are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170307
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  • 81
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    How good is good agreement: Evaluating the reliability of quantum-mechanically calculated observablesData organization and analysis were performed on the PROPHET system, a national computer resource sponsored by the Chemical/Biological Information Handling Program, National Institutes of Health, U.S.A. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 467-478 
    Details
    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 practical value of a wave function derives from its ability to estimate or predict the chemical and physical properties of the electronic structure which it describes. Reliability is defined as a property to be evaluated on the basis of (i) the magnitude of the difference between the measured and calculated values of the observable together with (ii) the sign of the difference, (ii) the number and nature of observables correctly estimated, and (iv) the number and type of electronic structures that are correctly estimated. Systematic statistical comparison implies the existence of both internally consistent sets of wave functions for homologous series of molecules and their corresponding experimental values together with reliable error estimates. The most complete data base currently available for comparison is the spectroscopic constants for the first and second row diatomic hydrides. Utilizing appropriate statistical comparison techniques, four approximations (CEPA, PNO-CI, GTO-SCF, and STO-SCF) are compared among themselves and against experimentally measured values. The CEPA approximation yields differences from experiment that approximate a normal error distribution, while the other approximations show systematic departures from experiment. Two values, ωe and ωeχe, for SH exhibit differences large enough to cast doubt upon the calculated value, the experimental value, or both.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170308
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  • 82
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    Electronic Resource
    Fock coordinate function method for separation of spin variables in transition density matrices (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 415-428 
    Details
    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 Fock generating function method is employed for the separation of spin variables into two-particle transition density matrices. Their spatial components introduced by McWeeny are expressed through Schrödinger's coordinate wave functions. Some nontrivial integral relations between these components and the charge and transition spin density matrices are obtained. The interrelation between the mentioned spatial components and the Matsen-Poshusta symmetrized density matrices of an arbitrary spatial function is found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170304
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  • 83
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    Masthead (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980) 
    Details
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170401
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  • 84
    Electronic Resource
    Electronic Resource
    SCF Theory of multiplet states (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 725-736 
    Details
    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 theory of multiplet monodeterminantal states is described from a comprehensive viewpoint. In this context, the formalism and derived theorems are developed, as well as the description of a SCF closed-shell-like structure, namely the hypermultiplet. Numerical applications are discussed taking as a model the H2O molecule and its first positive ion. Wave functions of double ζ-quality, with computed molecular properties of 16 states are given.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170413
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  • 85
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    Electron correlation effects in SCF+CI wave functions - Fermi and coulomb correlation holes in HCN (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 759-774 
    Details
    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 Coulomb correlation hole distribution function has been computed with respect to various reference centers in the HCN molecule, using standard SCF+CI type wave functions. The extent to which statistical correlation between unlike-spin electrons is introduced into an SCF wave function through the inclusion of configuration interaction has been assessed by an examination of the range and depth of such holes, and compared with the behavior of analogous Fermi distribution functions. Our results show that the range of Fermi correlation is consistently longer than that of the corresponding Coulomb correlation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170416
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  • 86
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    Slater-orbital molecular integrals by numerical Fourier-transform methods. II. Four-center integrals over is orbitalsPresented in part at the Microsymposium on Quantum Chemistry, Starý Smokovec, Czechoslovakia, 1977. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 747-757 
    Details
    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 four-center nonplanar electron repulsion integrals over 1s Slater-type atomic orbitals are considered by a numerical Fourier-transform method. It is shown that the highly oscillating integrand appearing in the Fourier inversion formula could be successfully treated by using Tchebyscheff quadrature. The resulting formulas are thoroughly discussed with particular emphasis on their numerical features and convergence properties. It follows that the aforementioned integrals may be calculated with a good accuracy with a moderate amount of computing time.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170415
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  • 87
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    Investigation of tertiary structure of a series of DNA compact forms by the small-angle X-ray scattering methodPresented at the International Conference on Quantum Chemistry, Biology, and Pharmacology held at Kiev, U.S.S.R., September 1978. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 813-817 
    Details
    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: This work describes the investigation of the space organization of DNA compact forms and DNA-protein complexes by the small-angle x-ray scattering method. A plane texture was disclosed in dehydrated DNP films. Compact DNA particles formed in the presence of poly(ethylene glycol) reveal ordered structures having a periodicity of 84 Å. Various morphological forms of crystals of CTA-DNA were used to obtain small-angle x-ray patterns of the single-crystal type.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170420
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  • 88
    Electronic Resource
    Electronic Resource
    Asymptotic forms of atomic scattering factors and momentum densities (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 833-844 
    Details
    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: Within the framework of the nonrelativistic Schrödinger equation, the Coulomb field case is used to assess the range of validity of the Thomas-Fermi statistical theory of atoms. In particular, attention is focused on (a) the x-ray scattering factor, which is the Fourier transform of the electron density; and (b) the momentum density. In each case the predictions of the statistical theory are compared with the exact results for the Coulomb potential. These can conveniently be calculated using earlier work of Fock. Some assessment is also made of the accuracy of the statistical approximation for the kinetic energy density; this is of interest in connection with the density functional approach. Finally, some brief comments are made on the relation between the self-consistent Thomas-Fermi method and the Hartree theory for atoms.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170503
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  • 89
    Electronic Resource
    Electronic Resource
    Global analysis of composite particles (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 915-930 
    Details
    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 theory of vibrations of a composite particle when vibrational amplitudes are not constrained to be small according to the Eckart conditions is developed using the methods of differential topology. A global classical Hamiltonian appropriate for this system is given, and for the case of the molecular vibration-rotation problem, it is transformed into a global quantum Hamiltonian operator. It is shown that the zeroth-order term in the global Hamiltonian operator is identical to the Wilson-Howard Hamiltonian; higher-order terms are shown to give successively better approximations to the large amplitude problem. Generalized Eckart conditions are derived for the global classical Hamiltonian; the quantum equivalent of these conditions along with the quantum equivalent of the Eckart conditions are given. The spectrum of the global Hamiltonian operator is discussed and it is shown that the calculation of the vibration-rotation energy states of the system reduces to the same straight-forward procedure, the solution of a secular determinant, as was carried out for the Wilson-Howard Hamiltonian at a later time by Nielsen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170507
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  • 90
    Electronic Resource
    Electronic Resource
    Approximate theoretical determination of molecular static polarizabilities (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 955-968 
    Details
    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 polarizabilities are computed using ab initio SCF wave functions and second-order perturbation theory with special attention given to the use of a shifted denominator. Rather small basis sets are used, in order to obtain reasonable values at a reduced cost. Results are presented for H2, CO, H2O, C2H4, OCS, C6H6, Cl2, Br2, I2.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170510
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  • 91
    Electronic Resource
    Electronic Resource
    Theoretical description of fluidity in biological membranes: Rotational motion in lipid hydrocarbon chains (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 983-993 
    Details
    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 mathematical model to relate order and rotational motion in lipid hydrocarbon chains in biological membranes is proposed. Schrödinger equations with suitable potential functions for C—C rotations in lipid hydrocarbons chains have been solved to obtain wave functions characterizing these motions. For a free chain a threefold potential function has been assumed. The effect of collisions between neighboring chains in a membrane is considered by including another term (δ function) in the potential function.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170513
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  • 92
    Electronic Resource
    Electronic Resource
    Masthead (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980) 
    Details
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170501
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  • 93
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    Electronic Resource
    Absorption UV spectroscopy and electronic structure of ionic and tautomeric forms of hydroxy and methoxy derivatives of cytosine and adenine, and of some 5-substituted analogs of pyrimidinesPresented at the International Conference on Quantum Chemistry, Biology, and Pharmacology held at Kiev, U.S.S.R., September 1978. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 803-811 
    Details
    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 individual absorption spectra of various ionic and tautomeric species of some derivatives of nucleic-acid components have been determined by computer handling of the summary spectra of these compounds measured at different pH values. These individual spectra have been decomposed into separate bands represented by log-normal curves and corresponding to different electronic transitions. Using the parameter system calculated earlier for the molecules of the vitamin B6 family, the calculation of the electronic spectra and electronic structure of various ionic and tautomeric species of the molecules studied have been carried out in the π-electron approximation. These properties have also been calculated by the all-valence electronic method CNDOS. The calculated results correlate well with both approximations and with our experimental spectral data. The localization of the molecular electronic excitation studied on the transition to the S1 and T1 states is considered in connection with the reactivity in these states.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170419
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  • 94
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    Electronic Resource
    Incomplete basis set problem. IV. Perturbative corrections to pair energiesThis research was supported by a grant from the Research Corporation. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 895-905 
    Details
    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 partitioning of the molecular Hamiltonian into the occupied and virtual orbital spaces and their orthogonal complement is introduced and used to develop a perturbation expansion of the exact ground-state energy relative to the Hartree-Fock energy computed using an incomplete basis set. The leading perturbation corrections to pair energies due to using the incomplete basis set are considered in detail. Summations of certain classes of pair contributions are discussed and a resummed correction is obtained.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170505
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  • 95
    Electronic Resource
    Electronic Resource
    Energy levels for perturbed Morse oscillators (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 931-942 
    Details
    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 energy levels and perturbation expansions for the expectation values of arbitrary powers of position for a perturbed Morse oscillator are obtained by application of the hypervirial and Hellmann-Feynman theorems, solely in terms of the unperturbed energy. We obtain expressions for the first-order corrections for (1 - e-aq )m for 4 ≤ m ≤ 8 and the expressions to second and third order for the quartic perturbation. A numerical application to the CO molecule is made.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170508
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  • 96
    Electronic Resource
    Electronic Resource
    Ab initio Hartree-Fock-Slater calculations of polysulfanes H2Sn (n = 1-4) and the ions HSn- and Sn2- (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 969-974 
    Details
    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 ab initio Hartree-Fock-Slater procedure was applied to the calculation of the electronic structure of polysulfanes, H2Sn (n = 1-4) and the ions HSn- and Sn2-. Charge densities, overlap populations, and deprotonation energies are calculated; the latter appear well correlated with the first and second acidity constants.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170511
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  • 97
    Electronic Resource
    Electronic Resource
    Behavior of molecular potential energy curves for large nuclear separations (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1143-1166 
    Details
    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
    Description / Table of Contents: Nous prouvons par des méthodes géométriques élémentaires et dans le cadre de l'approximation de Born-Oppenheimer, que quand les noyaux d'une molécule sont dissociés en amas séparés dans l'espace, les énergies moléculaires discrètes tendent vers la somme des énergies des sous-systèmes isolés. Nos méthodes montrent aussi que les projections spectrales associées au spectre moléculaire discret tendent asymptotiquement vers des sommes directes de projections spectrales convenables pour les sous-systèmes isolés. Ces résultats s'appliquent à n'importe quel système de particules qui interagissent par des potentiels de paire s'annulant asymptotiquement. Nous prouvons que le développement en 1/R pour des courbes de potentiel moléculaires discrètes est asymptotique quand R → ∞, et nous discutons le comportement des coefficients de ce développement pour l'état fondamental de H2+.Wir beweisen durch elementare geometrische Methoden und im Rahmen der Born-Oppenheimer-Näherung, dass, wenn die Kerne eines Moleküls in räumlich separierten Clusters dissoziiert werden, die diskreten Molekülenergien Summen der Energien der isolierten Untersysteme zustreben. Unsere Methoden zeigen auch, dass die mit dem diskreten Molekularspektrum assoziierten Spektralprojektionen asymptotisch direkten Summen von geeigneten Spektralprojektionen für die isolierten Untersysteme zustreben. Diese Ergebnisse sind für irgendein System von Teilchen gültig, die durch asymptotisch verschwindende Paarpotentiale wechselwirken. Wir beweisen, dass die Entwicklung in 1/R für diskrete molekulare Potentialkurven wenn R → ∞ asymptotisch ist, und wir diskutieren das Verhalten der Koeffizienten dieser Entwicklung für den Grundzustand von H2+.
    Notes: We prove by elementary geometric methods and within the Born-Oppenheimer approximation that as the nuclei of a molecule are dissociated into spatially separated clusters, the discrete molecular energies approach sums of the energies of isolated subsystems. Our methods also show that the spectral projections associated with the discrete molecular spectrum asymptotically approach direct sums of suitable spectral projections for the isolated subsystems. These results apply to any system of particles interacting by asymptotically vanishing pair potentials. We prove that the 1/R expansion for discrete molecular potential curves is asymptotic as R → ∞, and we discuss the behavior of the coefficients of the 1/R expansion for the ground state of H2+.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170609
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  • 98
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    Electronic Resource
    Electronic interactions of N-methyl-N-nitrosourea with DNA and its chemical modifications (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1221-1227 
    Details
    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: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170616
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  • 99
    Electronic Resource
    Electronic Resource
    Quantum model for transport through membranes (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1191-1200 
    Details
    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
    Description / Table of Contents: Dans le present article on considére un nouveau modèle pour le transport moléculaire à travers des membranes, qui a été introduit antérieurement par Hosur. Dans ce modèle, la membrane est assimilée à une barrière de potentiel, en déterminant le flux matériel à travers de la měme partant dès le coefficient de transmission de la barrière, en supposant l'existence d'une différence d'énergie parmi les molécules qui appartiennent à les fluides d'une et d'autre cǒté de la membrane. On obtient ainsi, une expression pour le flux dans le cas de pétites différences d'énergie, qui a été particularisée au cas ou la difference d'énergie est due à un gradient de température, un gradient de concentration ou à tous les deux gradients agissant ensemble. Dans tous les cas, sous certaines conditions, on obtient des equations qui sont formellement identiques à celles obtenues par la thermodynamique des processus irréversibles.
    Abstract: In vorliegendem Artikel wird ein von Hosur eingeführtes Modell für Transport durch Membranen untersucht. In diesem Modell wird die Membran mit einer Potentialschwelle assimiliert, und der Materialfluss durch die Membran wird vom Transmissionskoeffizient der Schwelle bestimmt, wobei es wird angenommen, dass ein Energieunterschied unter den Molekülen an den beiden Seiten der Membran existiert. Für den Fall wo dieser Energieunterschied klein ist wird eine Gleichung für den Transport erhalten. Diese wird spezialisiert zu den Fallen wo der Energieunterschied von einem Temperatur-oder Konzentrationsgradient oder beiden zusammen verursacht wird. In allen Fallen werden-mit gewissen Begrenzungen-Gleichungen erhalten, die mit denen der Thermodynamik irreversibler Prozesse formal identisch sind.
    Notes: In the present paper a new model for the transport through membranes, introduced previously by Hosur, is considered. In this model, the membrane is assimilated to a potential barrier, and the material flow through the membrane is determined from the transmission coefficient of the barrier, assuming the existence of an energy difference among the molecules placed at both sides of the membrane. An equation for the transport, in the case of small energy differences, is obtained, which is particularized to the cases that the energy difference is caused by a temperature gradient, a concentration gradient, and both gradients acting together. In all cases, under certain limitations, formally identical equations to those of the thermodynamics of irreversible processes are obtained.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170613
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  • 100
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    Nonrigidity effects of fragments of membrane-active complexonsPresented at the International Conference on Quantum Chemistry, Biology, and Pharmacology held at the Institute for theoretical Physics, Kiev, U.S.S.R., 18-22 September, 1978. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1229-1235 
    Details
    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 nonrigid molecule symmetry group for methylamine is determined as a set of permutations and permutation inversions for two situations. In the first case the internal rotations of the methyl group and NH2 group are included and the second case the transition of a hydrogen atom from the methyl group to NH2 group is also included. In both cases the energy level splitting of the rigid model of the methylamine is found, nuclear statistical weights of the split levels are calculated, and sections rules for the allowed dipole transitions are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170617
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