Multi-orbital Hubbard model with infinite-range coulomb coupling

Abstract

In this paper, we study the role of degeneracy in the Hubbard model featuring infinite-range Coulomb coupling. We put forward its exact solution for any dimension alongside analytical expressions for the one-dimensional (1D) lattice, thus generalizing the solution proposed by Hatsugai and Kohmoto for a single orbital. The ground-state phase diagram is also addressed against the particle density, interaction strength, and orbital number. We show that increasing the orbital number and/or the Hund’s hole coupling favors the phases associated to aligned spins within orbitals. Standard thermodynamic quantities in the grand canonical ensemble are further evaluated in 1D.