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  • Computational Chemistry and Molecular Modeling  (3)
  • Wiley-Blackwell  (3)
  • Periodicals Archive Online (PAO)
  • 1985-1989  (3)
  • 1980-1984
  • 1989  (2)
  • 1987  (1)
  • 1983
  • 1
    Digitale Medien
    Digitale Medien
    Surface states in deformed and perturbed diatomic crystals (1989)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 36 (1989), S. 553-561 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electronic properties of a one-dimensional diatomic crystal have been analyzed by using the MO-LCAO method in the tight binding approximation, with mathematical techniques involved in setting up and solving difference equations. The approach gives the exact sets of analytic solutions for both localized and nonlocalized states. The theory of surface states is developed as a characteristic value problem. To illustrate the method the surface states for a semiinfinite crystal which contains a local imperfection at the surface were examined. It appears that this method has advantages over previous methods developed to solve surface problems in crystalline lattices.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560360503
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Approximate solutions of Heisenberg Hamiltonians (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 903-925 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Even when each atom of a 2n-center cluster or molecule only brings one active electron in one atomic orbital, the size of the Heisenberg Hamiltonian matrix increases as C2nn. Simple truncations of this matrix would result in size consistence defects, as evident from the isomorphism between Heisenberg and configuration interaction (CI) matrices. Geometry-dependent Heisenberg Hamiltonians derived from accurate ab initio calculations on the two-center systems have proved to be very efficient for conjugated hydrocarbons and for alkali metals; in order to apply this approach to intermediate size systems (10-20 centers), a rational procedure is proposed consisting of the selection of a truncated set of determinants (of low energy) and a dressing of the truncated Hamiltonian matrix under the perturbation of the other determinants. The second order dressing is analogous to a so-called “shift Bk procedure” or Generalized Degenerate Perturbation theory and is weakly dependent on an E0 parameter. Tests performed on various 8- and 10-atom systems show the accuracy of the procedure. An iterative selection of the truncated basis set and proper choices of the E0 values allow one to obtain the whole lower part of the spectrum. The calculated geometries are satisfactory. Some preliminary applications are reported concerning the C12H14 dodecahexene linear chain, perfectly fitting with previous extrapolations.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560310606
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    The tautomerism of 1,2,3-triazole, 3(5)-methylpyrazole and their cations (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 426-433 
    Details
    ISSN: 0192-8651
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Biochemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Informatik
    Notizen: The annular tautomerism of 1,2,3-triazole and 3(5)-methylpyrazole is discussed by means of a combination of theoretical calculations and experimental (ICR) gas-phase basicities and acidities. In the gas phase 1,2,3-triazole exists as the 2H-tautomer, whereas both tautomers of 3(5)-methylpyrazole are of similar energy. The solvent effects on these prototropic equilibria are discussed taking into account solvent properties as polarity/polarizability, acidity, and basicity. In nonhydrogen bonding solvents, the difference in dipole moments between both tautomers plays a role that has usually been underestimated.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcc.540100318
    Standort Signatur Erwartet Verfügbarkeit
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