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  • 1
    Electronic Resource
    Electronic Resource
    Cubic-grid Gaussian basis sets for electron scattering calculations. I. Definition and construction (1995)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 53 (1995), S. 419-429 
    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 propose a new type of Gaussian basis sets for use in calculations of electron scattering by molecules. Instead of locating the basis-set functions on the atomic centers of the target molecule, we place primitive s-type Gaussians at the positions of a cubic lattice with a regular grid. The grid and the Gaussian exponent are fixed so as to give the best representation of the plane-wave function. Plane-wave functions and Green functions obtained by means of the cubic-grid basis set are tested graphically against exact functions and functions expressed by means of a conventional Gaussian basis set. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560530408
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  • 2
    Electronic Resource
    Electronic Resource
    Cubic-grid Gaussian basis sets for electron scattering calculations. II. Matrix elements (1995)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 53 (1995), S. 431-436 
    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 this article, we report an efficient computational procedure for electron scattering matrix elements in the previously developed cubic-grid Gaussian basis sets. The Green function matrix elements derived for the cubic-grid basis set are simpler and easier to calculate than are those available in the literature for conventional Gaussian basis sets. Special features of the cubic-grid basis sets may also be exploited for a very efficient computation of Coulomb and exchange integrals. Inelastic scattering amplitudes for vibrational excitations may be efficiently calcualted in the harmonic approximation by numerical differention of the T-matrix elements. © 1995 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560530409
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Cubic-grid Gaussian basis sets for electron scattering calculations. III. Effect of basis-set translation and size on the calculated cross section (1995)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 53 (1995), S. 437-450 
    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: Previously developed cubic-grid basis sets of various sizes were used for the calculation of cross sections for elastic and inelastic electron scattering by the He and Ne atoms and the H2O molecule by the T-matrix expansion method. The aim was to test the invariance of calculated cross sections with respect to the translation of the target molecule and to examine the effect of basis-set size on the results. We also present a simple procedure for accounting for long-range interactions from the part of space that lies outside the volume that contains the cubic-grid basis set. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560530410
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  • 4
    Electronic Resource
    Electronic Resource
    Ag vibrational levels of cyclobutadiene on a new potential energy surface (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 415-420 
    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: GVB/[5s3p1d/3s1p] energies were calculated for 31 geometries of cyclobutadiene in the D2h point group. These geometries differed in the values of the symmetrized internal coordinates for two CC stretching and one CCH bending modes. The data points were fitted to the expansions of in powers of . Variational calculations provided the following energies of the lowest Ag vibrational levels (with respect to the vibrational ground state): 4.4; 1161.2; 1162.3; 1304.0; 1322.8; 1920.3; and 1991.0 cm-1.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560400313
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  • 5
    Electronic Resource
    Electronic Resource
    Perturbation theory for open-shell systems: Simulation of the UHF states by means of the perturbed RHF wave functions (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 24 (1983), S. 141-148 
    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: Second-, third-, and selected fourth-order contributions to the correlation energy were calculated for a series of simple open-shell systems by means of the previously developed double-perturbation theory in the restricted MO formalism. It was found possible to assign some of the diagrams to self-consistency effects and to approximate in this way the EUHFSCF - ERHFSCF energy difference. A comparison is made with a more rigorous approach, in which the UHF ground-state wave function is expressed as a first-order perturbation expansion based on the RHF reference wave function. Distinguishing between “self-consistency” and “correlation” diagrams for open-shell systems in the RHF formulation represents a special case of a more general problem met in any double-perturbation treatment, such as, e.g., treatments of systems in the external field or perturbation expansions with noncanonical orbitals.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560240202
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  • 6
    Electronic Resource
    Electronic Resource
    MM2 study on the conformation of N-acetyl-L-amino acid N′-methylamides with aliphatic side chain and their Nα-methyl derivatives (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 12 (1991), S. 829-838 
    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: ϕ - ψ maps have been calculated by the MM2(87) potential for the Nα-acetyl derivatives of Gly, Ala, Val, and Tle methylamides and their Nα-methyl substituted derivatives to interpret the 1H NMR and CD spectra of these compounds. From the critical examination of the available theoretical and experimental evidence it follows that in the series of Nα unsubstituted Ala, Val, and Tle derivatives the importance of the second lowest energy conformation (C5) is increased and that eventually it becomes the lowest energy conformation instead of C7eq. With the Nα-methyl substituted Ala and Val derivatives, the lowest energy conformation seems to be C7eq. Performance of MM2(87) was tested for the ϕ - ψ map of the Ala derivative by comparing it with other theoretical data available in the literature.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540120707
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  • 7
    Electronic Resource
    Electronic Resource
    MM2 study of 20-hydroxy-4,7,13,16-tetraoxa-1,10-diazabicyclo [8,8,3] heneicosane and its formation controlled by hydrogen bonding (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 11 (1990), S. 837-847 
    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 van der Waals-type parameter set has been developed for hydrogen bonding in the MM2(85) force field to reproduce the structures and binding energies of complexes (H2O)2, (CH3OH)2, H3N … H2O, H3N … HOCH3, (CH3)3N … H2O, and HCONH2 … H2O reported in the literature. The MM2(85) force field modified in this way was then applied to the title compound to explain its unexpected stability, unusual properties of its hydroxyl group, and solvent effect on the reaction mechanism in the condensation of Kryptofix 22 ® with epichlorohydrine.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540110707
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