First-principles elastic and bonding properties of barium chalcogenides

First-principles calculations have been used to investigate the elastic and the bonding properties of barium chalcogenides BaS, BaSe, and BaTe at equilibrium as well as high pressures using full potential-linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT). We used local density approximation (LDA) with and without generalized gradient approximation (GGA), which is based on exchange-correlation energy optimization to calculate the total energy. A numerical first-principles calculation of the elastic constants was used to calculate C11, C12, and C44 for these compounds. As the experimental elastic constants are not available; hence our results were only compared with the available theoretical values obtained at equilibrium volume. Additionally, the nature of the chemical bond in these compounds was analyzed. We investigated the bonding character of BaS, BaSe, and BaTe in terms of electronic charge density and found out that the strong charge localization around the anion side let these compounds to behave as the most ionic ones among the alkaline-earth chalcogenides family.