Investigation of on-site interorbital single-electron hoppings in general multiorbital systems

A generalized multiorbital Hubbard model, which includes on-site interorbital electron hoppings, is introduced and studied on an arbitrary basis. In a general system the on-site interorbital single-electron hopping may exist realistically between two orbitals, e. g., the excitation of electrons or flow of electrons between two hybridized states, and is hence one of the most basic interactions like the intersite hopping and the on-site Coulomb interactions. It is shown in this work how the higher order interactions can be well incorporated (or generated) in the equations of motion from the basic interactions in the Hamiltonian, which has made it possible and also given a self-consistent way to investigate these higher order correlation effects. The two-orbital Hubbard model is studied numerically in the paramagnetic case to demonstrate the influence of the single-electron hopping effect, leading to a change of the shape of the bands and a shrinking of the difference between the two bands. Inclusion of the on-site interorbital hopping suppresses the so-called orbital-selective Mott transition.