The density matrix in may-electron quantum mechanics III. Generalized product functions for beryllium and four-electron ions

Abstract

The theory of generalized product functions is extended to non-orthogonal group functions in the case of two groups. Calculations on beryllium and on some four-electron ions are based on such group functions, and are compared with similar calculations using orthogonal group functions. It is shown that, in the case of the systems examined, the strong orthogonality restriction is not severe.