Multiband d-p Model for the Description of Sr₂RuO₄

We study electronic structure of multiband d-p model describing RuO₄ layer such as realized in Sr₂RuO₄. The model takes into account nearest-neighbor anisotropic ruthenium-oxygen and oxygen-oxygen hoppings, intra-atomic Coulomb interaction, Hund's exchange and in addition spin-orbit coupling on ruthenium. The RuO₄ is universally considered as a pure $t_{2g}$ system (with $e_{g}$ orbitals empty) due to sizable gap between $t_{2g}$ and $e_{g}$ levels. We show that ruthenium $e_{g}$ orbitals are in fact occupied, similarly like showed earlier for CoO₂ layers.