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  • 1
    Electronic Resource
    Electronic Resource
    Anharmonic contributions to the inversion vibration in 2-aminopyrimidine (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 656-662 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The out-of-plane vibrations of the amino group in 2-aminopyrimidine have large amplitudes, and cannot be properly described within the harmonic approximation. The normal mode analysis carried out at this level of approximation at the restricted Hartree–Fock level and at the second-order Møller–Plesset perturbation theory level failed to match the experimental transition frequency of ν≈200 cm−1 of the inversion vibration in this compound. In an effort to better understand this vibration motion, we went beyond the harmonic approximation. The inversion vibration was treated as being uncoupled from all other nuclear degrees of freedom. An internal coordinate (ω) was chosen whose displacement mimicked the out-of-plane distortion of the amino group during the inversion vibration. Electronic energy was calculated at the second-order Møller–Plesset perturbation theory level at selected values of ω to form a double-well curve describing a model potential within which the nuclei move during the vibration. This potential was incorporated into a one-dimensional Hamiltonian, and vibrational energy expectation values were variationally determined by utilizing the harmonic wavefunctions as the basis set. Two sets of calculations were performed: one in which the mirror plane of symmetry was preserved throughout the vibrational deformation limiting the internal coordinates to 17, and another in which the symmetry was unconstrained permitting description by 3N−6=30 internal coordinates. These calculations resulted in prediction of the v=0→v=1 transition energy of ν=130.1 cm−1 and ν=206.7 cm−1, respectively, reasonably matching the experimental value of ≈200 cm−1. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470099
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  • 2
    Electronic Resource
    Electronic Resource
    Polarisation control of light by light in a nonlinear polymer (1998)
    Springer
    Applied physics 67 (1998), S. 211-215 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 42.70; 42.65; 78.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050495
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    An analytical solution of isotopomeric enumerations for C2v cyclic odd-numbered carbon clusters Cn (1997)
    Springer
    Journal of radioanalytical and nuclear chemistry 219 (1997), S. 69-71 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The current experimental and computational research in carbon clusters pointed out a need for enumeration of all possible12C/13C isotopoments of the C2v cyclic odd-numbered carbon clusters Cn. It is shown that the number of the isotopomers is given by 2k−1(2k−1+1) withk=(n+1)/2. Some illustrative computed structure and energy data for the clusters are reported, too.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02040267
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  • 4
    Electronic Resource
    Electronic Resource
    The influence of the transmission coefficient of the boundary on the diffusion in a solid surrounded by vacuum (1997)
    Springer
    Journal of mathematical chemistry 21 (1997), S. 413-434 
    Details
    ISSN: 1572-8897
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mathematics
    Notes: Abstract The calculations leading to the differential equations of statistical kinematics inside a solid and near the boundary between a solid and vacuum are given. The influence of the transmission coefficient of the boundary on the concentration of the diffusing material in solids is taken into account by introducing the length of extrapolation expressed by the polynomial of arbitrary order depending on the needed accuracy. The obtained length of extrapolation is influenced not only by the diffusion parameters and the boundary’s characteristic feature but also by the initial distribution of concentration and by the time of diffusion. The presence of an external force is neglected. The numerical calculation for the planar diffusion of hydrogen in a palladium monocrystal is given as an example. The present method may be particularly useful for diffusion in thin layers and membranes, or when the detailed information on the distribution of diffusing material near the boundary between a solid and vacuum is needed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019143023927
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  • 5
    Electronic Resource
    Electronic Resource
    Analytic first derivatives for explicitly correlated, multicenter, Gaussian geminals (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 63 (1997), S. 991-999 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Variational calculations utilizing the analytic gradient of explicitly correlated Gaussian molecular integrals are presented for the ground state of the hydrogen molecule. Preliminary results serve to motivate the need for general formulas for analytic first derivatives of molecular integrals involving multicenter, explicitly correlated Gaussian geminals with respect to Gaussian exponents and coordinates of the orbital centers. Explicit formulas for analytic first derivatives of Gaussian functions containing correlation factors of the form exp(-βrij2) are derived and discussed. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 991-999, 1997
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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