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  • 1
    Electronic Resource
    Electronic Resource
    Electronic structure of tetraphenyldithiapyranylidene: A valence effective Hamiltonian theoretical investigation (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 4474-4483 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a theoretical investigation of the electronic structure of tetraphenyldithiapyranylidene (DIPSΦ4) using the nonempirical valence effective Hamiltonian (VEH) method. Molecular geometries are optimized at the semiempirical PM3 level which predicts an alternating nonaromatic structure for the dithiapyranylidene (DIPS) framework. The VEH one-electron energy level distribution calculated for DIPSΦ4 is presented as a theoretical XPS simulation and is analyzed by comparison to the electronic structure of its molecular components DIPS and benzene. The theoretical VEH spectrum is found to be fully consistent with the experimental solid-state x-ray photoelectron spectroscopy (XPS) spectrum and an excellent quantitative agreement between theory and experiment is achieved when comparing the energies of the main peaks. A detailed interpretation of all the experimental photoemission bands is reported in the light of the VEH results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462810
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  • 2
    Electronic Resource
    Electronic Resource
    Theoretical determination of the geometric and electronic structures of oligorylenes and poli(peri-naphthalene) (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 8470-8480 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a theoretical investigation of the electronic structure of oligorylenes (from perylene to heptarylene, including also the naphthalene molecule) and their corresponding polymer poly(peri-naphthalene) (PPN) using the nonempirical valence effective (VEH) method. The geometry of the unit cell used to generate the polymer is extrapolated from the PM3-optimized molecular geometries of the longest oligorylenes. That geometry shows some bond alternation along the perimeter carbon chains and a bond length of ≈1.46 A(ring) is calculated for the peri bonds connecting the naphthalene units. The VEH one-electron energy level distributions calculated for oligorylenes are used to interpret the experimental trends reported for the first ionization potentials, redox potentials, and lowest energy optical transitions. An excellent agreement is found between theoretical estimates and experimental values. The VEH band structure calculated for an isolated chain of PPN is interpreted in terms of the molecular orbitals of naphthalene. The ionization potential, electron affinity, and bandwidths obtained for PPN suggest a large capacity to form conducting p- or n-type materials. The small band gap of 0.56 eV predicted for PPN from VEH band structure calculations is in good agreement with theoretical and experimental estimates calculated by extrapolating the data reported for the oligomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463418
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    MINDO/3 Study of the Rearrangement of 1-Methylcyclohexyl Cation to 1,2-Dimethylcyclopentyl Cation (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 7 (1986), S. 417-427 
    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: The rearrangement of the 1-methylcyclohexyl cation to the 1,2-dimethylcyclopentyl cation has been studied by MINDO/3 calculations, as an application of the branching mechanism model for cycloalkanes. Possible intermediates and transition states have been characterized by diagonalization of their Hessian matrixes. Two nonequivalent pathways, α and β scissions, are relatively close in energy. The calculated transition states are almost equivalent in energy to those found for cyclohexyl cation. Hence, the energy barriers are higher for the rearrangement of the 1-methyl than for cyclohexyl cation, because the former is less stable than the latter.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540070405
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    Paper (German National Licenses)
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