Phase stability and pressure-induced semiconductor to metal transition in crystalline GeSe2

The structural and electronic properties of crystalline GeSe 2 are studied using ab initio density functional theory. GeSe 2 exists in a variety of phases; here eight phases, six previously synthesized and two hypothetical, are investigated within the local density approximation and the generalized gradient approximation (GGA). The results show that the GGA correctly describes the energetics of the GeSe 2 even with variations in charge density of layer GeSe 2 structures. The stability of the phases studied is discussed, and the possible phase transitions under pressure are predicted and compared to experiment. The electronic structure of GeSe 2 confirms, for the first time, that the high-pressure CdI 2 -type phase is metallic which may produce the semiconductor to metal transition in the GeSe 2 system under pressure.