The pairwise-correlated generalized valence bond model of electronic structure. V. A multiconfiguration overlap approximation for gvb pair energies

Abstract

A multiconfiguration overlap approximation for GVB pair correlation energies is developed and applied to the ground states of H2 and LiH. The exploratory studies presented indicate that if we explicitly include the effects from three low-lying excitations beyond the GVB wave function, we obtain an overlap approximation for GVB molecular pair correlation energies that is accurate to 0.001 hartree (0.5 kcal/mole) for all internuclear distances from 0 to ∞, and gives the proper asymptotic form for van der Waals interactions.