Optical and magnetic property of [formula omitted]

A tight binding parameterization of the band structure, along with a mean field treatment of Hund, electron–electron, and electron–lattice couplings, is used to obtain the full optical conductivity tensor of [formula omitted] as a function of temperature. We predict the magnetic phase transition causes striking changes in the functional form and magnitude of the optical absorption. Our results differ from those obtained by the local density-functional approximation techniques. Possible origins of the discrepancy are discussed.