Optical absorption analysis of quaternary molybdate- and tungstate-ordered double perovskites

Quaternary-ordered double perovskite A sub(2)MM'O sub(6) (M = Mo,W) semiconductors are a group of materials with a variety of photocatalytic and optoelectronic applications. An analysis focused on the optoelectronic properties is carried out using first-principles density-functional theory with several U orbital-de-pendent one-electron potentials applied to different orbital subspaces. The structural non-equivalence of the atoms resulting from the symmetry has been taken in account. In order to analyze optical absorption in these materials deeply, the absorption coefficients have been split into inter- and intra-non-equivalent species contributions. The results indicate that the effect of the A and M' atoms on the optical properties are minimal whereas the largest contribution comes from the non-equivalent 0 atoms to M transitions.