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443. VESCF: Variable Electronegativity Self-Consistent
Field
by Julia C. Tai, Department of Natural Sciences, The University of Michigan, Dearborn, Michigan 48128 and N. L. Allinger, Department of Chemistry, The University of Georgia, Athens, Georgia 30602 This program calculates the electronic spectra of molecules up to 24 pi orbitals by a modified Pariser- Parr method with inclusion of singly and doubly excited configurations. The molecular orbitals are obtained by a variable electronegativity self-consistent field (VESCF) treatment.Detailed procedure and input parameters used for carbon, nitrogen and oxygen orbitals are described in the following publications: 1. N. L. Allinger, J. C. Tai, and T. W. Stuart, Theoretica Chim. Acta, 8, 101 (1967). 2. N. L. Allinger, T. W. Stuart, and J. C. Tai, J. Am. Chem. Soc., 90, 2809 (1986). 3. J. C. Tai and N. L. Allinger, Theoretica Chim. Acta, 12, 261 (1868). 4. J. C. Tai and N. L. Allinger, ibid, 15, 133 (1969). One feature of the program that is not described in any previous publication is the option to vary the number of doubly excited configurations that are included in the final configuration interaction (CI) matrix through use of the parameter IDELTA.Doubly excited configurations Vijkl with k+l-(l+j) equal to or greater than IDELTA will not be included. This option is introduced for two reasons: 1) to cut down the computation time, and 2) to reduce the number of configurations so that the total number in any CI matrix will not exceed 400 (the upper limit imposed by the program). It should be noted that the optimum value of IDELTA to use is currently under investigation. FORTRAN IV (IBM) Lines of Code: 3163 |