Band Structure Calculation and Optical Properties of Ag3AsS3 Crystals

In the study, band structure calculation in the points of high symmetry of the first Brillouin zone and alongside the lines that connect them has been derived by using CASTEP programs in which the pseudopotential method with the basis in the form of plane-waves is realized. The calculated value of the lattice parameters using GGA functional is well correlated with experimental data. According to the band diagram that was built for the Ag3AsS3 crystal using GGA method, band gap has an indirect type. The calculated value of the band gap is = 1.22 еV. The experimental value of the band gap obtained by Tauc’s method is = 2.01 еV, = 2.17 еV. Full and partial density of N(E) states for contributions of separate atoms has been calculated. As a result, the top of the valence band is formed by 3p-states of S atoms and the bottom of the conduction band is formed by 5s-states of Ag atoms and 3p-states of S atoms.