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  • 1
    Electronic Resource
    Electronic Resource
    An MC-SCF procedure using an orthogonal transformation represented by a direct sum of two-by-two rotations (1985)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 28 (1985), S. 203-211 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N molecular orbitals are transformed to K(≦N) molecular orbitals, which are appropriate for an orbital optimization by two-by-two orthogonal rotations among themselves. This transformation is determined by using the second-order structure of the variational energy surface. The optimum K/2 rotation angles are exactly determined. This helps to ensure the reliability of convergence. K/2 two-by-two rotations are repeated among these K transformed orbitals. Then, two-electron molecular integrals are calculated by transformations among only 16 elements and by a permutation among K4/8 elements. Calculational time is considerably reduced compared with that of more usual transformations. Test calculations have been carried out on the ground state of CO. It shows that this procedure brings the calculation to the local region rapidly and reliably.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560280204
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  • 2
    Electronic Resource
    Electronic Resource
    A method of calculation of the matrix elements between the spin-projected nonorthogonal Slater determinants (1995)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 54 (1995), S. 235-242 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the resonating Hartree-Fock calculation, we have to calculate the matrix element between spin-projected nonorthogonal Slater determinants (S dets). The matrix element between coherently spin-rotated S dets are given by a linear transformation of the spin-projected ones. Using the inverse transformation, we get the projected matrix elements from the coherently spin-rotated ones. By appropriately choosing the angles of the spin rotation, the required computational time is considerably reduced. © 1995 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560540406
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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