An open-shell random phase approximation

Abstract

A formalism is proposed for extending the random phase approximation to open shell systems. This method is based upon use of a central field model to obtain zeroth order energies and wavefunctions and utilizes the equations-of-motion approach of Rowe (1972). The basic equations of the usual random phase approximation are preserved, so that many of the characteristics of the solutions of the extended problem can be obtained using traditional arguments. Characteristics and limitations peculiar to the open-shell problem are discussed.