Valence bond model analysis of homonuclear alkali and halogen diatomics on the basis of exchange perturbation theory. Part 2. Heteronuclear compounds

Exchange perturbation theory is applied, in the framework of the valence bond method, to study chemical bonding in heteronuclear alkali and halogen diatomics. It is shown that, using a basis set of atomic functions limited to a very few spherical or polarized Gaussian-type orbitals, whose characteristic parameters are determined a priori from those of the corresponding homonuclear diatomics given in a previous publication [1), it is possible to reproduce expeximental data on the equilibrium distances, ground state dissociation energies, and vibrational constants with an accuracy comparable to that obtained on the basis of extensive ab initio calculation