Superconductivity in the multiband Hubbard model with long-range Coulomb repulsion

A multiband CuO Hubbard model is studied which incorporates long-range (LR) repulsive Coulomb interactions. In the atomic limit, it is shown that a charge transfer from copper to oxygen ions occurs as the strength of the LR interaction is increased. The regime of phase separation is replaced by a uniform state with doubly occupied oxygens. As the holes become mobile a superfluid condensate is formed, as suggested by a numerical analysis of pairing correlations and flux quantization on one-dimensional chains. The competition between charge-density wave and superconductivity is also analyzed. It is argued that the results are also applicable to two dimensions.