Symmetric group approach to relativistic CI. II. Reduction of matrices in the spin space

Abstract

An algorithm for the evaluation of matrix representations of products of permutation operators and of one-and two-electron spin-dependent operators in a spin-adapted basis of the N-electron spin space is presented. In particular, the case of the basis functions in which pЈ electrons are described by products of singlet-coupled pairs is considered in Ž . detail. The N-electron spin integrals are, in this case, reduced explicitly to the N y pЈ electron ones.