First principles study of structure, electronic and optical properties of Y₃Fe₅O₁₂ in cubic and trigonal phases

First principles calculations have been performed to investigate the structure, electronic and optical properties of Y₃Fe₅O₁₂. Both the cubic and trigonal phases have been considered in our calculation. The calculated structural parameters are slightly larger than the experimental values. The band structures show that Y₃Fe₅O₁₂ in cubic and trigonal phases have direct band gaps of 0.65 and 0.17 eV. The calculations of dielectric function, absorption, extinction coefficient, refractive index, energy loss function and reflectivity are presented.