Modification of the Born—Mayer Potential Function as Applied to the Crystalline Alkali Halides

Abstract

The repulsion constant ρ in the Born—Mayer potential function is assigned values which are different for like- and unlike-ion pairs in such a way that large deviations from the observed compressibilities of the lithium halides, attributable to marked anion—anion repulsion, are removed. Lattice parameters in excellent agreement with the experimental ones are than obtained using alternative sets of ``basic radii'' based on differently evaluated ionic radii, but an indeterminacy characteristic of the Born—Mayer equation is shown to affect markedly the calculated like-ion overlap-repulsive contributions. The possibility of considerable error in the calculated results through lack of correction for ion asymmetry is discussed. The calculated electron affinities, which are unaffected by these uncertainties, agree approximately with the most precise determinations by other methods.