First principles study of barium chalcogenides

In this study, ab initio calculation results of the vibrational properties and elastic parameters as well as characteristic Debye temperature and Poisson's ratios of two barium chalcogenides, BaSe and BaS, which crystallize in NaCl-type structure, were presented. Calculations were based on plane wave basis sets together with ultrasoft pseudopotentials in the framework of density functional theory (DFT) with generalized gradient approximation. Phonon dispersion spectra were obtained using the first principles linear response approach of the density functional perturbation theory (DFPT). The detailed total energy calculations were performed in order to obtain elastic constants using distortions on cubic phase. The calculated structural, elastic, and thermal parameters of BaSe and BaS systems agree well with the available experimental data and theoretical calculations.