Investigation of structural, electronic, optical, thermoelectric, and stability properties of Na

contextThe present work illustrates the first systematic assessment of the structural, electronic and optical characteristics of the cubic halide double perovskite compounds Na

methodsWe have performed DFT calculations using FP-LAPW method employed in WIEN2k with a GGA exchange correlation function. Firstly, we performed the structural optimization to get the optimal structure of the lowest energy configuration. Afterwards, Electronic properties such as band structures and DOS were computed. To get the more accurate bandgap we used the TB-mBJ approach with the PBE-GGA functional. The optical properties such as dielectric function, reflectivity, refractive index, etc. were calculated using the enhanced bandgap values for detailed representation of the spectra. The transport coefficients of thermoelectric materials were calculated using a Boltzmann approach under the constant relaxation time approximation employed in BoltzTraP code. The method for determining the elastic constants is based upon the finite strain theory, while the thermodynamic properties are determined using the quasi-harmonic Debye model in Gibbs2 code.