Outer-Shell Overlap Integrals as a Function of Distance for Halogen—Halogen, Halogen—Alkali, and Alkali—Alkali Ions in the Alkali Halide Lattices

Abstract

The outer s‐ and p‐electron overlap integrals involving ns, np σ, and np π orbitals have been computed for all combinations of ion pairs in all of the alkali halide lattices. The free‐ion closed‐shell Hartree—Fock wavefunctions were used in all calculations. The halogen—alkali (H—M) overlaps are listed at the equilibrium internuclear distances. The halogen—alkali (H—M), halogen—halogen (H–H), and alkali—alkali (M—M) overlap integrals were computed at several internuclear distances and were found to follow the exponential form S ab=A exp(—r ab/ρ). Values of A and ρ are listed for all combinations of overlaps in the alkali halides. Various convenient combinations of sums of squares of overlaps are also given as a function of distance for all the combinations in the alkali halide lattices.