METAL-INSULATOR-TRANSITION IN AN ONE-DIMENSIONAL HUBBARD-LIKE MODEL WITH DEGENERACY AND CRYSTALLINE FIELD SPLITTING

We consider the SU(N) generalization of Lieb and Wu's Bethe-ansatz sol ution of the one-dimensional Hubbard model, where N is a degeneracy co mposed of spin and orbital degrees of freedom. At T = 0 the model has a Mott metal-insulator transition at a critical value U-c(N) for a ban d-filling of exactly one electron per site. U-c increases with N, bein g zero for N = 2 and U-c = 3.466 as N --> infinity. We discuss grounds tate properties along the metal-insulator boundary for two bands(N = 4 ) split by a crystal field Delta. The bands could represent to the z(2 ) and x(2) - y(2) 3d-orbitals of CuO2.