STRUCTURAL PHASE-STABILITY IN BASE

The band structure of BaSe in both NaCL-type (B1) and CsCl-type (B2) s tructures is determined using the self-consistent linear muffin-tin or bital method within the atomic sphere approximation (LMTO-ASA). In agr eement with the earlier observations, the band gap is found to be indi rect in both B1 and B2 structures. The calculated values of the band g aps are compared with the experimental values. From the ASA total ener gy calculations, the structural phase stability of BaSe is studied. At ambient conditions BaSe is found to be stable in the B1 structure. It undergoes a structural transition to the B2 structure at about 55 x 1 0(8) Pa, associated with a volume reduction of 14.3%. The equilibrium lattice constants for both B1 and B2 structures and the transition pre ssure are compared with earlier experimental results.