Band and filling-controlled transitions in exactly solved electronic models

We describe a general method to study the ground-state phase diagram of electronic models on chains whose extended Hubbard Hamiltonian is formed by a generalized permutator plus a band-controlling term. The method, based on the appropriate interpretation of Sutherland’s species, yields under described conditions a reduction of the effective Hilbert space. In particular, we derive the phase diagrams of two new models; the first one exhibits a band-controlled insulator-superconductor transition at half-filling for the unusually high value $U_c=6t;$ the second one is characterized by a filling-controlled metal-insulator transition between two finite regions of the diagram.