GUTZWILLER APPROXIMATION IN DEGENERATE HUBBARD MODELS

Abstract

The details of the Generalized-Gutzwiller-Approximation in degenerate Hubbard models are presented. It is found that the metal-insulator transition occurs at a finite correlation Uc when the average number of electrons per lattice site is an integer. A derivation is given for the general expression of Uc(x, N) which reproduces all previously known Gutzwiller solutions, including that of the boson Hubbard model. The Uc depends sensitively on both the band degeneracy N and the filling x. Effects of the lattice structure on the metal-insulator transition and the effective mass are discussed.