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.