Orbital orderings and optical conductivity of SrRuO(3) and CaRuO(3): first-principles studies.

The Jahn-Teller (JT) distortion induced orbital order and optical conductivity in SrRuO(3) and CaRuO(3) are investigated by first-principles calculations. The total energy and optical conductivity of all the spin ordering states of SrRuO(3) and CaRuO(3) are calculated in the LDA+U scheme with U(eff) = 2.5 eV. The down-spin t(2g) of Ru show antiferromagnetic-like orbital order in the a-b plane. We observe a d-d transition peak at an energy of about 1.0 eV in the calculated optical conductivity and analyze the reason for it not being observed in previous experiments.