First principles study of electronic structure and optical properties of double perovskite Ba2(InM)O6 [M=Nb, Ta]

The structural, electronic and optical properties of double perovskite oxides Ba2(InNb)O6 and Ba2(InTa)O6 are investigated by full-potential linearized augmented plane wave method based on density functional theory under generalized gradient approximation. The real and imaginary parts of the dielectric function and the optical constant (refractive index) are calculated. The calculated spectra are compared with the experimental results and are found to be in reasonable agreement. The interband contributions to the optical properties of these perovskite oxides have been analyzed.