First principles study of structural, elastic, electronic, and optical properties of the cubic perovskites AVO₃ (A = Ca and La)

Abstract

Using first principle method based on the plane wave pseudo potential calculations and the local density approximation (LDA), we have investigated some basic fundamental properties of CaVO₃ and LaVO₃ promising cubic perovskites (A = Ca and La). First, the equilibrium lattice parameters have been established to be in a good agreement with the available experimental data. For values of applied pressures up to 30 GPa and at zero temperature absolute, there is no phase transition was observed. Our results show that both compounds were mechanically stable. Static finite strain technique is employed to obtain the elastic constants and their pressure dependence. By analyzing the ratio between the bulk and shear moduli, it was found that LaVO₃ is ductile than CaVO₃ compound in nature. The metallic character of the studied perovskites was distinguished via their calculated band structure. We have found that O 2p states and V 3d states play a major role in the optical transitions as initial and final states, respectively. Total density of states at Fermi level revealed that LaVO₃ should be more conductor than CaVO₃. The increase in the antibonding state between the oxygen atoms yield in stiffness decreases. This was deduced when carrying out overlap population analysis. The Mulliken charge transfer suggests that CaVO₃ is more covalent (less ionic) than LaVO₃. The optical constants, including the dielectric function, and optical reflectivity including electron energy loss, refractive index, optical conductivity, and the linear absorption spectrum were established for radiation up to 20 eV.