Ab initiovalence-bond calculations on HF, LiH, LiH+and LiF

Abstract

Ab initio multi-structure valence-bond calculations of the potential energy curves of HF, LiH, LiH+ and LiF are presented. The atomic orbital basis sets used in these calculations were contracted gaussian minimum orbital basis sets of double zeta quality, augmented by a few extra s and p-type orbitals. The extra orbitals permit a reasonably accurate description of F- and H- relative to their neutral atoms and also provide extra flexibility to the molecular wavefunction. The calculated potential energy curves behave correctly at large internuclear separations and yield dissociation energies which are within 10 per cent to 16 per cent of the experimental value. These calculated dissociation energies are improved slightly by application of empirical atomic corrections within the framework of the orthogonalized Moffitt method. Dipole moment curves for the neutral diatomics are also presented, as are some comparisons with calculations using smaller basis sets. The calculations described in this paper were inte...