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  • 2020-2023
  • 1980-1984  (41)
  • 1981  (41)
  • Computational Chemistry and Molecular Modeling  (41)
  • 1
    Electronic Resource
    Electronic Resource
    Direct calculation of resonant states in reactive scattering. Application to linear triatomic systems (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 19 (1981), S. 611-635 
    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 direct method for calculating resonant states in reactive scattering is suggested, permitting us to obtain the characteristics of multichannel resonances (partial width amplitudes). The method is based on the construction of a Laurent expansion of the scattering matrix S(∊ -iΓ/2) in the complex plane. The position of the poles of the S matrix are derived by solving the dynamical problem with complex energy values. The residue at the pole gives all the information concerning the partial widths. The method is applied to a linear triatomic reactive scattering problem. The properties of the resonant states in the H + H2 system are calculated as an example. Two broad resonances are found which have not been reported in previous calculations. The interference of overlapping resonances is shown to have a profound effect on the energy dependence of the transition probabilities.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560190414
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  • 2
    Electronic Resource
    Electronic Resource
    Erratum (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 19 (1981), S. 1221-1221 
    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.560190635
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  • 3
    Electronic Resource
    Electronic Resource
    Nonconservation of excitons as a mechanism of light-energy capturing (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 19 (1981), S. 33-42 
    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 analysis of nonstationary processes, taking place in exciton systems in consequence of the nonconservation of the number of elementary excitations, is presented and it is pointed out to a new possibility of light-energy capturing which exists in ecological systems due to the nonconservation of excitons. It is shown that, due to the nonconservation, the one-dimensional molecular chain is able to capture permanently the light energy of the order of 50 keV to 5 MeV. A part of the captured energy is expected to have a role in internal bioprocesses. It is also shown that the system is a seat where the processes of continuous creations and annihilations of pairs of excitons having opposite momenta take place with a probability of the order of 10-4 to 10-2. Further investigations would allow to identify biological phenomena caused by those processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560190105
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  • 4
    Electronic Resource
    Electronic Resource
    MNDO calculations for compounds containing aluminum and boron (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 2 (1981), S. 433-445 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Parametrization of MNDO for aluminum and comparisons of calculated molecular properties with experimental values indicate the general usefulness of MNDO to study aluminum-containing compounds. Although results are not as good as for molecules containing only C, H, N, and O, they are nevertheless accurate enough to be useful, especially when predictive biases noted in this article are considered. Inclusion of the d orbital in the MNDO scheme may improve the aluminum results. Results for boron-containing molecules not previously reported are also reported in this article.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540020412
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  • 5
    Electronic Resource
    Electronic Resource
    Hypervirial analysis of enclosed quantum mechanical systems. I. Dirichlet boundary conditions (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 19 (1981), S. 521-532 
    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: Diagonal hypervirial relations are applied to enclosed one-dimensional systems when wave functions obey Dirichlet boundary conditions. A general formula for the energy is derived and it shows a striking difference with the usual formulas through an “extra” term. It constitutes a generalization of previous ones for the virial theorem when there exist nonusual boundary conditions. The values obtained are compared with other approximate methods. Several extensions are proposed.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560190406
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  • 6
    Electronic Resource
    Electronic Resource
    Some thermodynamic parameters for hydroxy amino acids: Bicine and tricine (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 385-391 
    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: pKa(NH3+) values of N,N-dihydroxyethylglycine (bicine) and N-[tris(hydroxymethyl)methyl]-glycine (tricine) have been determined by the Irving-Rossotti method in an aqueous medium at 25, 30, 35, 40, 45, and 50°C and at different ionic strengths (I = 0.1, 0.5, and 1.0). Plots between pKa(NH3+) and 1/T for various ionic strengths have been obtained and the values of slopes have been used to calculate the ΔH, ΔS, and ΔG for the dissociation reactions of bicine and tricine. The ΔH, ΔS, and ΔG values for bicine were found to be 10.6 ± 0.6 kcal mol-1, -1.9 ± 1.8 e.u., and 11.1 ± 0.06 kcal mol-1, respectively, and for tricine 11.2 ± 0.6 kcal mol-1, 1.6 ± 1.6 e.u., and 10.7 ± 0.06 kcal mol-1, respectively. The pKa(NH3+) values decrease with rise in temperature but the influence of ionic strength is not significant.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560200211
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  • 7
    Electronic Resource
    Electronic Resource
    Interaction of the mutagenic base analogs O6-methylguanine and N4-hydroxycytosine with potentially complementary bases (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 543-554 
    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: Infrared spectroscopy has been employed to study possible base pair interactions, in nonpolar media, between O6-methylguanine and uracil, cytosine and adenine; and between derivatives of N4-hydroxycytosine and adenine. The association constants of O6-methylguanine with uracil, cytosine, and adenine are well below 1M-1, whereas those for interaction of 1-methyl-N4-methoxycytosine and its 5-methyl derivative with adenine are identical, K = 14M-1. The significance of the latter finding is discussed in relation to the conformation of the exocyclic N4-methoxy group. Quantum chemical calculations, with the aid of the perturbation method, were carried out for the interaction of O6-methylguanine with uracil, cytosine, and adenine, to establish the most energetically favoured configurations for interactions of the free bases, and of the same base pairs in the B form of DNA. The role of the conformation of the exocyclic  - OCH3 group in O6-methylguanine is discussed. The relevance of both the experimental and theoretical results to mutagenesis by O6-methylguanine and N4-hydroxycytosine is examined.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560200226
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  • 8
    Electronic Resource
    Electronic Resource
    Hypervirial analysis of enclosed quantum mechanical systems. III. Unsymmetrical boundary conditions (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 623-632 
    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: New theoretical developments based upon hypervirial analysis of enclosed systems are given. Systems which obey unsymmetrical boundary conditions are analyzed. Several results which were given by the authors in two previous communications are generalized.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560200305
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  • 9
    Electronic Resource
    Electronic Resource
    Chemistry of excited states. XI. Interpretation of photoelectron spectra by final state single CI method within semiempirical formalismsPart X: G. Kluge and M. Scholz, Wiss. Z. Karl Marx Univ. Leipzig Math. Naturwiss, Reihe 28, 573 (1979). (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 669-682 
    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 single excited doublet states of some small molecule cations calculated by CI method in the framework of semiempirical CNDO and INDO models are correlated with the photoelectron spectra of the parent molecules. The purity of the Koopmans transitions is used to discuss the one-particle interpretation of photoelectron bands by comparison with nonempirical many-body calculations. Furthermore, empirical relations are applied with respect to the evaluation of shake-up energies.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560200309
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  • 10
    Electronic Resource
    Electronic Resource
    Generalized Racah method for the evaluation of CFP for mixed electronic configurations (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 763-774 
    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 Racah method, proposed for the evaluation of coefficients of fractional parentage (CFP) for single shell configurations, is generalized for the cases of two and more than two shells. On the basis of the generalized Racah method, we have evaluated one-particle CFP for all states of svpμ electronic configurations. Two-particle CFP are expressed through one-particle CFP and Racah coefficients.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560200316
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