Superconductor-insulator transitions in a Hubbard chain with nearest-neighbor and bond-charge interactions

We consider a half-filled generalized Hubbard chain with electron-hole symmetric correlated hopping and on-site and nearest-neighbor repulsions U and V, respectively. In addition to the insulating charge- and spin-density wave phases for large V and U, respectively, we identify a phase with dominant superconducting correlations at large distances for small U and V. Using two Berry phases tone associated to the charge and the other to the spin degrees of freedom) as discrete order parameters, we construct a phase diagram for the three thermodynamic phases. (C) 1998 Published by Elsevier Science B.V. All rights reserved.