Study of the metal-insulator transition and superconducting correlations of a generalized Hubbard model

We study the metal-insulator transition of a generalized Hubbard model in which the magnitude of the nearest-neighbor hopping depends on the occupations of the sites involved. Numerical results for finite chains at half-filling show that when 0 < t(AB) < t(AA) = t(BB), where t(AB) is the term which modifies the number of doubly occupied sites, there exist a finite range of values of the Coulomb repulsion U > 0 for which the system is metallic. This is consistent with a Hartree-Fock calculation. The metallic phase collapses to one point, U = 0, in the Hubbard limit. In the metallic phase we obtain that the superconducting correlations are the dominant ones, at least for doped systems.