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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 94 (1996), S. 233-245 
    ISSN: 1432-2234
    Keywords: CASSCF ; VB ; Orbital optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is demonstrated how exact transformations of full CI spaces may be carried out for general, non-unitary orbital transformations, and a detailed description of an efficient implementation of this scheme is presented for Slater determinants. It is then shown how this technology may be employed in the optimization of general VB wave functions with respect to both orbital and structure coefficients. This may be done in a straightforward manner, incorporating first and second derivatives of the variational parameters.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0040-5744
    Keywords: Key words: CASSCF ; VB ; Orbital optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  It is demonstrated how exact transformations of full CI spaces may be carried out for general, non-unitary orbital transformations, and a detailed description of an efficient implementation of this scheme is presented for Slater determinants. It is then shown how this technology may be employed in the optimization of general VB wave functions with respect to both orbital and structure coefficients. This may be done in a straightforward manner, incorporating first and second derivatives of the variational parameters.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 70 (1998), S. 637-650 
    ISSN: 0020-7608
    Keywords: excited states ; modern valence bond theory ; CASVB ; spin-coupled wave function ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The valence bond description of excited states is considered in the context of the CASVB approach, with emphasis on the simultaneous optimization of orbitals and structure coefficients for highly general types of wave function, as well as the close connection to the complete active space self-consistent field (CASSCF) method. In addition to fully variational optimization of modern valence bond (VB) wave functions, one may also generate compact representations of CASSCF wave functions, essentially irrespective of their nature. Consequences of generalizing the CASVB methodology to other than the lowest-lying state of a given symmetry are explored for both the overlap- and energy-based optimization criteria. The methodology is illustrated by means of applications to the 21Ag state of trans-1,3-butadiene, the c˜1A1 state of methylene, and the first excited singlet state of benzene.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 637-650, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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