THE COVALENT BOND IN CRYSTALS. II. PARTIALLY IONIC BINDING,
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 ec*/e = 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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1967
- Accession Number
- AD0657433
Entities
People
- J. C. Phillips
Organizations
- University of Chicago