Ion-ion interaction potentials and their application to the theory of alkali halide and alkaline earth dihalide molecules

Abstract

Interaction potentials of many ion pairs are calculated using the model presented in our previous paper [J. Chem. Phys. 56, 3122 (1972)]. In the calculation of the interactions of two ions, the electron density of the combined system of the ions is assumed to be equal to the sum of the two separate ionic electron densities. The Coulomb energy contribution to the interaction energy is calculated directly from the charge distribution of the nuclei and the assumed electron density. The non-Coulombic part of the interaction energy is calculated from the electron density using the electron gas energy expression in terms of the local electron density. The ions treated are the alkali, the alkaline earth, and the halide ions. The calculated ion-ion interaction potentials are applied to the theory of alkali halide and alkaline earth dihalide molecules. The predicted molecular bond energies, bond lengths, and vibration frequencies agree quite well with existing experimental data.