Theoretical study of CaO, CaS and CaSe via first-principles calculations

Abstract

ab initio Calculations were performed to study the properties of CaO, CaS and CaSe alkaline earth chalcogenides in the B1 (NaCl) and B2 (CsCl) phases. The calculations were based on the density functional theory (DFT) within generalized gradient approximation (GGA). Results of structural properties (equilibrium lattice parameters, bulk moduli, its first pressure derivative) of both phases, and results of the properties of phase transition from B1 to B2 phase (transition pressure, compression ratio at the phase transition) were reported. Elastic properties of the B1 phase of these compounds, such as elastic constants C11, C12, and C44, shear modulus (G), Young's modulus (E), Poisson’s ratio (σ), Kleinman parameter (ξ), and anisotropy factor (A) were investigated at ambient conditions. The band structure and density of states were studied, too, for the B1 structure of these compounds. The results are in good agreement with the available experimental and other theoretical results. Keywords: Alkaline earth chalcogenides, Ab initio calculations, Structural properties, Phase transition, Elastic properties, Electronic properties