First-principles calculations of Mg1−xCuxSiP2 alloys with x = 0.0, 0.25, 0.5, 0.75 and 1.0

An ab initio method based on density functional theory, Perdew-Burke-Ernzerhof (PBE) type generalized gradient corrections to exchange and correlation, and projector-augmented waves (PAW) is performed to investigate structural, electronic and optical properties of Mg1−xCuxSiP2 with x = 0.0, 0.25, 0.5, 0.75 and 1.0. The electronic band calculation results demonstrate that MgSiP2 and CuSiP2 are semiconductor with a direct band gap in chalcopyrite structure, while Mg.75Cu0.25SiP2, Mg0.5Cu0.5SiP2 and Mg0.25Cu0.75SiP2 compounds show a half metallic nature. The gradual substitution of Cu element by MgSiP2 accompanied by a decrease in the lattice constant and energy band gap value.