Projected quasiparticle calculations in large model spaces

Abstract

A general formalism is presented, by means of which number projected BCS quasiparticle calculations require only a little more computational effort than unprojected ones, even in large model spaces. It is a generalized and improved combination of known formalisms. Its advantages over those methods are discussed. The formalism is very well suited for applications where the BCS superfluidity parameters are different for initial and final states, such as particle transfer reactions and pairing vibrations. Extensive formulas are given.