HIGH-PRESSURE PHASES OF ALSB FROM AB-INITIO THEORY

We present the results of an ab-initio study of the ground state prope rties and the high pressure phase diagram of AlSb. We have analyzed th e structural parameters and the total energy of AlSb in the rocksalt, cesium chloride, beta-tin, zincblende. and nickel arsenide-type struct ures, performing first principles self-consistent local density calcul ations with nonlocal pseudo potentials. From the energy versus volume diagram we obtain that at 4.7 GPa AlSb transforms to the NiAs-type str ucture, like other III-V AlX compounds. This is in disagreement with a recent experimental study that reports a transition to a B-tin struct ure. We also predict a second transition to the CsCl-type structure at 39.5 GPa.