First principles study of the structural, electronic, optical, elastic and thermodynamic properties of CdXAs2 (X=Si, Ge and Sn)

The first principles calculations were performed by the linearized augmented plane wave (LAPW) method as implemented in the WIEN2K code within the density functional theory to obtain the structural, electronic and optical properties for CdXAs2 (X=Si, Ge and Sn) in the body centered tetragonal (BCT) phase. Optical features, such as dielectric functions, refractive indices, extinction coefficient, optical reflectivity, absorption coefficients, and optical conductivities, were calculated for photon energies up to 40 eV. The six independent elastic parameters (C11, C12, C13, C33, C44 and C66) were evaluated and thermodynamic calculations within the quasi-harmonic approximation were used to give an accurate description of the pressure–temperature dependence of the thermal-expansion coefficient, bulk modulus, specific heat, Debye temperature, entropy and Grüneisen parameters. Based on the semi-empirical relation, we have determined the hardness of the materials for the first time at different temperature and pressure.