On the generalized multi-reference Brillouin-Wigner coupled cluster theory

The generalized multireference Brillouin-Wigner coupled cluster theory is presented for the case of a single root function. The Bloch-like equation and the Lippmann-Schwinger-like equation for the generalized multireference Brillouin-Wigner perturbation theory are obtained. These equations are then applied to the solution of the multireference coupled cluster equations for the case in which a single root function is required.