Symmetry simplifications of space types in configuration interaction induced by orbital degeneracy
✍ Scribed by K. Balasubramanian
- Publisher
- John Wiley and Sons
- Year
- 1981
- Tongue
- English
- Weight
- 748 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
Abstract
Symmetry simplifications are introduced in configuration interaction (CI) by reducing the number of symmetry‐allowed space types if there is degeneracy in some of the molecular orbitals by constructing the unique space types. A new symmetry group which we call the configuration symmetry group is defined and is shown to be expressible as a generalized wreath product group. Generating functions are derived for enumerating the equivalence classes of space types. A double coset method is expounded which constructs the representatives of all equivalence classes of space types using the cycle index of generalized wreath product and the double cosets of label subgroup with generalized wreath product in the symmetric group S~n~, if n is twice the number of occupied and virtual orbitals. Method is illustrated with CI using the localized orbitals of polyenes, CI in benzene, and atomic CI for several reference states.