Exact diagonalization scheme for the degenerate two-orbital Hubbard model on a ring

Abstract

The two-orbital degenerate Hubbard model proves to be a powerful tool in the investigation of several 3d and 4d transition metal oxides where orbital degeneracy is known to play a crucial role. We present here a finite-size cluster study of this model where an exact numerical diagonalization procedure is used, based on the implementation of the symmetries generated by the spin, the pairing and the orbital pseudospin operators. The technique is then applied to the solution of the model on a four-site ring, and an explicit comparison is presented between the behavior of the spin, charge and orbital gaps as the on-site Coulomb repulsion is varied.