Theoretical investigation of the structural, elastic, electronic and optical properties of the ternary indium sulfide layered structures AInS2 (A = K, Rb and Cs)

Ab initio calculations were performed to investigate the structural, elastic, electronic and optical properties of the ternary layered systems AInS₂ (A = K, Rb and Cs). The calculated structural parameters are in good agreement with the existing experimental data. Analysis of the electronic band structure shows that the three studied materials are direct band-gap semiconductors. Density of states, charge transfers and charge density distribution maps were computed and analyzed. Numerical estimations of the elastic moduli and their related properties for single-crystal and polycrystalline aggregates were predicted. The optical properties were calculated for incident radiation polarized along the [100], [010] and [001] crystallographic directions. The studied materials exhibit a noticeable anisotropic behaviour in the elastic and optical properties, which is expected due to the symmetry and the layered nature of these compounds.