Phase stability and elastic properties of CuGaSe2 under high pressure.

We report stability of high pressure phases and elastic properties in CuGaSe 2 , especially in cubic and orthorhombic phases. The distorted structures from F m 3 ¯ m and Cmcm consist of Pmmn , P21/m , Amm2 and P4/mmm were observed. Cu and Ga sites in F m 3 ¯ m and Cmcm can distinguish in the lower symmetry space groups which are P4/mmm and Amm2 , respectively. The enthalpy differences of an interested structure are compared in the pressure range 0–100 GPa. The phonon dispersion relation of CuGaSe 2 was studied, and found that the P4/mmm and Amm2 space groups give stability of phonon vibration modes. Moreover, we observe chemical bonds and elastic properties of CuGaSe 2 at high-pressure conditions. Elastic constants indicate mechanical stability of CuGaSe 2 in P4/mmm and Amm2 phases. Although CuGaSe 2 has become nonsemiconductor material in the P4/mmm and Amm2 phases, the strong of covalent bonds and sharing electrons are still increased by high pressure effect. [ABSTRACT FROM AUTHOR]