THE HIGH-PRESSURE BEHAVIOR OF ALSB

On the basis of the Gaussian nonlocal pseudopotential scheme, modifications of the structural and electronic properties of the indirect band-gap semiconductor AlSb with respect to the variation of the lattice constant are discussed. The results obtained for the valence and conduction band edge charge densities of this material for the zinc blende phase 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 blende 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 valence band edge charge densities as a function of volume shows that AlSb transforms at high pressure to the beta-Sn phase, which is a free-electron-like metal.