Accession Number:

AD0657433

Title:

THE COVALENT BOND IN CRYSTALS. II. PARTIALLY IONIC BINDING,

Descriptive Note:

Corporate Author:

CHICAGO UNIV ILL

Personal Author(s):

Report Date:

1967-01-01

Pagination or Media Count:

38.0

Abstract:

The general theory of covalent bonding developed in AD-657 432 is extended to heteropolar crystals. In diatomic crystals the theory depends on two parameters, an energy gap for each atom, or an energy gap for the medium and a polarizability parameter eta. The latter can be determined by comparison with empirical pseudopotential form factors the value obtained for GaAs and ZnSe which brings the form factors of the latter into agreement with the ion core form factors of Animalu and Heine, is eta -0.05 0.05 or - 0.05. This polarizability parameter can be used to estimate the effective charge ec defined by Callen, which describes the splitting of longitudinal and transverse optic modes of vibration at q 0. The result in GaAs is ece 0.14 0.04 or - 0.04, in rough agreement with the experimental value of 0.20 0.03 or - 0.03. The experimental values for ec may be used to estimate the gap parameters for each atom when complete data are available. Author

Subject Categories:

  • Physical Chemistry
  • Crystallography
  • Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE