First principles study of the structural, elastic, electronic and optical properties of CaSrTt (Tt=Si, Ge, Sn and Pb)

We present an ab initio study of the structural, elastic, electronic and optical properties of CaSrTt (Tt=Si, Ge, Sn and Pb) compounds. To more-accurately describe the properties of these materials, the calculations were based on the DFT theory with the generalized gradient approximation (GGA). In particular, the calculated lattice constants are in good agreement with the experimental results, with a deviation less than 0.67%, 2.74% and 1.7% for a, b and c, respectively. For the equilibrium volume, the deviation does not exceed 4.7%. Single-crystal elastic stiffness (Cij) values were calculated and the polycrystalline elastic moduli (B and G) were estimated utilizing Voigt, Reuss and Hill’s approximations. The electronic band-structure calculations indicate that these compounds are semiconductors, in agreement with the literature data on their Ae2Tt analogues. The dielectric function, refractive index, extinction coefficient, reflectivity spectrum and electron energy loss are calculated over a spectral range from 0 to 45 eV. unately, there is no available previous study for comparison.