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  • 1
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 1598-1607 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: A detailed 3D classical nonlinear mechanical analysis of HCN/HNC system is carried out and the results are compared with 2D quantum mechanical vibrational calculations as well as with the recent 3D quantum calculations of Bacic and Light. HCN is marked by regular behavior which persists at high energies when the stretching modes are excited. Chaotic trajectories located in the HNC well are those which lead to isomerization of HNC. The regular/irregular phase space structure agrees well with the corresponding assignment of quantum states. A multiple resonance among the vibrational modes of HCN, located at the top of the effective barrier of isomerization, is considered as the classical cause of the lack of delocalization of the wave functions found in the 3D quantum calculations.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 832-832 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 633-642 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: We propose and test a new general approach to the L 2 evaluation of quantum correlation functions for dissociative systems. This method introduces a split interaction representation (SIR) for the correlation function based on formally exact manipulations, and greatly enhances convergence of the correlation function with respect to the range of the L 2 basis, by suppressing the spurious "reflections'' from the "edges'' of the basis. The method is tested by applying it for the evaluation of flux autocorrelation function from which the quantal thermal rate constant is obtained by integrating it over time. Computations for the one-dimensional Eckart barrier show remarkable convergence of the flux autocorrelation function with respect to both the size and the range of the basis.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 1389-1402 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The influence of periodic orbits on quantum eigenfunctions and the dynamical evolution of wave packets is studied on a model 2D potential. The phase space structure is portrayed by constructing the diagram of characteristics of the most important families of periodic orbits. It is found that the topologies of eigenfunctions can be assigned to certain periodic orbits. Families bifurcating from the principal families, as well as irregular families which are not associated with the principal families, mark the eigenfunctions. The evolution of wave packets and the spectra which are produced from them show that quantum mechanically there is no communication among different resonance regions even at energies where chaos predominates in classical mechanics. This quantum regularity and localization is explained by testing the conjecture that the area of turnstiles (regions in the surfaces of section through which trajectories pass to get in or out the resonance zone) is less than Planck's constant. It is demonstrated that the systematic study of phase space structure through the families of periodic orbits in association with the solution of the time dependent Schrödinger equation for wave packets localized initially on such orbits provide the numerical techniques for studying highly excited species.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Chemical Physics 142 (1990), S. 345-359 
    ISSN: 0301-0104
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Chemical Physics 135 (1989), S. 347-356 
    ISSN: 0301-0104
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 18 (1997), S. 1011-1022 
    ISSN: 0192-8651
    Schlagwort(e): line search minimization algorithm ; topography ; multidimensional potential energy surfaces ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Informatik
    Notizen: The most robust numerical algorithms for unconstrained optimization that involve a line search are tested in the problem of locating stable structures and transition states of atomic microclusters. Specifically, the popular quenching technique is compared with conjugate gradient and variable metric algorithms in the Mg+Arn clusters. It is found that the variable metric method BFGS combined with an approximate line minimization routine is the most efficient, and it shows global convergence properties. This technique is applied to find a few hundred stationary points of Mg+Ar12 and to locate isomerization paths between the two most stable icosahedral structures found for Mg+Ar12. The latter correspond to a solvated and a nonsolvated ion, respectively. © 1997 John Wiley & Sons, Inc. J Comput Chem 18:1011-1022, 1997
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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