Ab initio calculations of structural, electronic, optical and thermodynamic properties of alkaline earth tellurides BaxSr1−XTe

Abstract Structural, electronic and thermodynamic properties of SrTe and BaTe compounds and their ternary mixed crystals Ba x Sr 1−x Te in the rock-salt structure have been studied with density functional theory (DFT), whereas the optical properties have been obtained by using empirical methods such as the modified Moss relation. The exchange-correlation potential was calculated using the generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof (PBE) and the local density approximation (LDA) of Teter–Pade (TP). In the present work, we used the virtual-crystal approximation (VCA) to study the effect of composition ( x ). The calculated lattice parameters at equilibrium volume and the bulk modulus for x =0 and x =1 are in good agreement with the literature data. Furthermore, the Ba x Sr 1−x Te alloys are found to be an indirect band gap semiconductor. In addition, we have also predicted the heat capacities ( C V ), the entropy( S ), the internal energy ( U ) and the Helmholtz free energy ( F ) of the parent compounds SrTe and BaTe.