Omega function for molecular systems: lithium hydride

Abstract

The omega function is defined as the best extended Hartee-Fock function that can be obtained after projection followed by antisymmetrization of a spin-unrestricted Hartree product of spinorbitals. This function is obtained by using a projector which gives rise to a linear combination of Slater determinants in which the α and β spinfunctions of each electron pair are interchanged. In previous papers, we proposed this model, and analized it in the ground states of three and four electron atomic systems. In this paper we present an application to a molecular system: LiH, and we compare the results with those obtained in other models.