ELECTRONIC-STRUCTURE AND STRUCTURAL PHASE-STABILITY IN BAS, BASE, ANDBATE

The self-consistent scalar-relativistic band structures for BaS, BaSe, and BaTe in NaCl-type and CsCl-type structures were obtained using th e tight-binding linear muffin-tin orbital method. From atomic-sphere a pproximation (ASA) total-energy calculations the structural phase stab ility in these compounds has been studied. The equilibrium lattice con stant for all three compounds agrees well with the experimental result s. The pressures at which these compounds undergo a structural phase t ransition from NaCl-type tb CsCl-type were calculated. The calculated pressures and volumes at transition agree well with the experimental r esults. The energy band gaps at ambient conditions in the NaCl-type st ructure and the volume dependence of band gaps in the CsCl-type struct ure were calculated. In addition the pressures and the volumes at whic h band overlap metallization occurs were also calculated and compared with experimental and other theoretical results.