Anisotropy and temperature dependence of the optical conductivity in LaMnO_3

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 LaMnO_3 as a function of temperature. We predict striking changes with temperature in the functional form and magnitude of the optical absorption. Comparison of our results to data will determine the Hund, electron-lattice, and electron-electron interactions.