STERNHEIMER ANTISHIELDING FACTORS OF F-, CL-, BR- AND I- - INFLUENCE OF APPROXIMATE FREE-ION AND CRYSTAL-ION POTENTIAL

Sternheimer ionic antishielding factors, γ∞, have been calculated for F-, Cl-, Br-, and I- in crystals using the Watson model within the nonrelativistic Hartree-Fock approximation and the perturbation numerical procedure. The free ion calculations of γ∞ using the Hartree-Fock wave functions have also been carried out in order to ascertain the solid-state effects. The free ion values of γ∞ change from -22.2, -55.1, -135.106, and -248.1 to -10.3, -34.8, -75.6, and -148.7 in solids for F-, Cl-, Br-, and I-, respectively. A major part of the discrepancy between the free ionic γ∞ values based on the Hartree-Fock and Hartree-Fock-Slater wave functions, as noted by the previous workers, is shown to arise from an inaccurate description of the self-interaction potential in the conventional Slater exchange approximation. © 1979 Springer-Verlag.