Ab initio study of pressure-induced phase transitions in the ordered Si50Ge50 alloy

First principles pseudopotential approaches are used to investigate the structural phase transitions of ordered Si50Ge50 alloy from zincblende to β-Sn to Imma then to simple hexagonal phase under high-pressure, the transition pressure of which are 12.3, 17.8 and 44.5 GPa, respectively. The electronic and structural properties of the four phases are also calculated.