Inter-orbital excitation modes in the two-orbital Hubbard model

Abstract Electronic states of the two-orbital Hubbard model are investigated by means of the equations of motion method. We identify the excitation modes which provide a complete operatorial basis in the local limit. They are dressed by spin and charge information of the other orbital within shell, providing the energy scale of inter-orbital interactions, U ′ and J , in addition to the intra-orbital one, U . The density of states (DOS) has five energy levels for each lower and upper Hubbard DOS, according to the electronic configuration within shell.