Variational Procedure for Open-Shell LCAO Multideterminant Wavefunctions. An Approach to the Excited-State Problem

Abstract

A procedure recently suggested for solving the LCAO problem is applied to open-shell LCAO wavefunctions built up by adding many determinants having the same spatial part which, commonly, are used to approximate the wavefunction of excited states. The procedure is extended to the case when an orthogonality condition must be explicitly imposed with given wavefunctions representing lower-energy states.