High pressure phases of AlSb from ab-initio theory

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