Perturbation theory and ionic models for alkali halide systems. I Diatomics

Abstract

Exchange perturbation theory is used to analyze the interaction energy and dipole moment of alkali halide diatomics. It is shown that classical ionic models for these systems can be derived by introducing a well‐defined set of assumptions to simplify the perturbation theory expressions. Further, it is demonstrated that extensions of the models to include distortion effects can be formulated and that these give rise to effective polarizabilities of the ions in the diatomic. Calculated spectroscopic properties based on a model including distortion effects show improved agreement with experimental data for the alkali halides.