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  • 1
    Electronic Resource
    Electronic Resource
    Quantum theoretical calculations of van der Waals interactions between molecules. Anisotropic long range interactions (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 11 (1977), S. 959-970 
    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: Presenting a relatively simple ab initio method to calculate full van der Waals interaction potentials between molecules, we give rules for the optimization of basis functions which permit the reliable evaluation of second order long range interactions. Closed expressions for the long range interaction energy are derived in which the orientational dependence is simplified to the utmost. Calculations show that even for molecules which have no dipole moment, such as ethylene, the strongly anisotropic electrostatic interactions are of the same magnitude as the dispersion interactions, but also that the anisotropic (“cross”) terms in the dispersion energy are about equal in size to the corresponding “quadratic” terms. Even though these anisotropic forces cancel to a large extent in the cohesion energy of the ethylene crystal, they can have important effects on some of the other crystal properties.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560110608
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Matrix elements between spin-bonded functions in a hole-particle formalism (1985)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 28 (1985), S. 609-630 
    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: Closed formulas are given for Hamiltonian matrix elements between spin-bonded functions in a holeparticle formalism. The derivation is based on Wick's theorem and the use of Jucys diagrams. The final formulas are only slightly more complicated than those for bonded functions in a particle formalism.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560280508
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Higher analytic derivatives. I. A new implementation for the third derivative of the SCF energy (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 179-199 
    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 is the first of a series of papers on the ab initio calculation of the second, third, and fourth derivatives of the energy with respect to nuclear coordinates. The knowledge of these derivatives yields anharmonic spectroscopic constants. Here, we present efficient formulae for the analytic evaluation of these derivatives for closed-shell SCF wave functions. We discuss our implementation of the third derivative formula, in particular the integral and vectorization procedures. Applications are reported for H2S, CHOF, and HCCF.
    Additional Material: 14 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560400203
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Charge calculations in molecular mechanics IV: A general method for conjugated systems (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 9 (1988), S. 288-297 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A general method for calculating pi charges based on the Hückel molecular orbital (HMO) approach is incorporated into an existing scheme for calculating partial atomic charges in saturated systems. The parametrization of the Hückel coulomb and resonance integrals is given based on (a) the CNDO pi densities and (b) the observed molecular dipole moments. The results for these two schemes are compared both with other theoretical methods and also with the observed dipole moments of a variety of conjugated and aromatic compounds. The dipole moment (DM) parametrization gives in general more consistent results and is to be preferred. The compounds studied include substituted olefins and aromatics (with substituents R, F, Cl, Br, I, OR), aldehydes, ketones, acids, esters, amides, and the heterocyclic ring systems of furan, pyrrole, pyridine, and indole.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540090403
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    Paper (German National Licenses)
    Fulltext
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