Detailed DFT studies of the electronic structure and optical properties of KBaMSe3 (M = As, Sb)

Abstract Bonding nature as well as the electronic band structure, electronic charge density and optical properties of KBaMSe 3 (M = As, Sb) compounds have been calculated using a full-potential augmented plane wave (FP-LAPW) method within the density functional theory. The exchange–correlation potential was handled with LDA and PBE-GGA approximations. Moreover, the Engel–Vosko generalized gradient approximation (EV-GGA) and the modified Beck–Johnson potential (mBJ) were also applied to improve the electronic band structure calculations. The study of band structure shows that KBaAsSe 3 /KBaSbSe 3 compounds have an indirect band gap of 2.08/2.10 eV which are in close agreement with the experimental data. The bonding nature has been studied as well using the electronic charge density (ECD) contour in the (1 0 1) crystallographic plane. It has been revealed that As/Sb–O atoms forms a strong covalent, while Ba–Se atoms form weak covalent bonding and the ionic bonding is mainly found between K and Ba atoms. Moreover, the complex dielectric function, absorption coefficient, refractive index, energy-loss spectrum and reflectivity have been estimated. From the reflectivity spectra, we found that KBaAsSe 3 compound shows greater reflectivity than KBaSbSe 3 , which means that KBaAsSe 3 compound can be used as shielding material in visible and also in ultra violet region.