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:
The symmetry adaptation procedure of Chen et al. [Sciencia Sinica 23, 1116 (1980)], which can account for the invariance properties of the Hamiltonian with respect to any finite point group G, is both modified and adapted to the Clifford algebra unitary group approach (CAUGA). From orthogonal symmetry adapted Mo's, one first constructs a pure configuration many-electron basis adapted to the chain U(ni) ⊃ G ⊃ G(s) in terms of the U(ni) Gel'fand-Tsetlin (GT) basis, where ni is the dimension of the irrep defining a given pure configuration, and G(s) designates the canonical chain supplying a unique labeling. The pure configuration basis is then coupled to the desired G-adapted states using the point group Clebsch-Gordan coefficients and the U(n1) ⊂ U(n1 + n2) ⊂ … ⊂ U(n) basis by using the permutation group outer-product reduction coefficients. This basis can be expressed in terms of the U(n) GT basis by using the U(n) subduction coefficients (SAC'S). The SDC'S are particularly simple for the highest weight states (Hess's) of various subproblems, which can be in turn represented through the U(2n) two-box Weyl tableaux of CAUGA. The non-HWS's are obtained by applying the U(ni) lowering generators to the HWS's. In this way we can directly obtain the spin and point group adapted CAUGA basis. The procedure is illustrated on a nontrivial example.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560320112
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