Extended Hartree—Fock Wavefunctions: General Theory of Optimized-Valence Configurations and Its Application to Diatomic Molecules

Abstract

A generalization of the extended Hartree—Fock scheme developed by the authors recently and called the method of optimized valence configurations is presented. This method continuously describes molecular formation and yields realistic potential curves, binding energies, and spectroscopic constants by accounting for the ``bonding correlation'' and relaxing the constraints of the single-determinant picture. Its adequacy for a single sigma bond was illustrated in our previous work; in this paper we present a general theory for correlating multiple shells and develop its application to diatomic molecules. The process and the general computer program developed to evaluate the best possible orbitals and mixing coefficients making up our wavefunctions have several interesting new computational features which are discussed. Results presented recently using this method are summarized.