Semiempirical valence bond potential energy surfaces for simple chemical reactions:1A′ states of H2O and H2F+

Abstract

A semiemprical valence bond method is employed to study the potential energy surfaces (PESs) of the lowest 1 A′ states of H2O and isoelectronic H2F+. The calculation is based on the search for the electronic configurations which play the most important rôle in the formation of the stable electronic states of the molecules and the relevant diatomic fragments. Several approximations are used to reduce the number of permutations in the calculation of the energy matrix. The Moffit atoms-in-molecule approximation is used to correct for the atomic errors arising from the poor basis set. The computed data for the lowest electronic states of OH, HF, HF+, H2O and H2F+, as well as the general behaviour of the PESs for different molecular geometries, are in good agreement with the available ab initio and experimental data.