THE HIGH-PRESSURE BEHAVIOR OF ALSB

On the basis of the Gaussian nonlocal pseudopotential scheme, modifica tions of the structural and electronic properties of the indirect band -gap semiconductor AlSb with respect to the variation of the lattice c onstant are discussed. The results obtained for the valence and conduc tion band edge charge densities of this material for the zinc blende p hase as a function of atomic volume up to 30% are used to analyze the bonding properties in AlSb. Trends in bonding are used to predict the pressure-induced structural phase transitions in AlSb from the zinc bl ende structure (N(c)=4) to the insulating rock-salt structure of NaCl (N(c)=6) or to a white-Sn-like structure (N(c)=6). Analysis of the val ence band edge charge densities as a function of volume shows that AlS b transforms at high pressure to the beta-Sn phase, which is a free-el ectron-like metal.