Dipole moment of open shell radicals using the Fock space multi -reference coupled cluster linear response approach: Full singles and doubles approximation

Abstract

In this paper we report the first results of Fock space multi-reference coupled-cluster linear response approach in the full singles and doubles approximation for one valence problem . . We present the test results for the OF, formoxyl, formyloxyl and hydroxyl radicals. Recently we have used an approximate version of this method where certain three-body parts arising out of contraction of Hamiltonian with the zero valence amplitudes were eliminated. Here we report the results for the full singles and doubles approximation. The

perturbative contribution of these additional terms to the effective Hamiltonian and the derivative effective Hamiltonian is analyzed. Explicit diagrams for the additional terms, referred here as three-body terms, are presented for one-valence hole and one –valence particle problem. These make a substantial difference to the dipole moment values.