BOUND ELECTRON PAIRS IN STRONGLY CORRELATED MODELS OF HIGH-TEMPERATURE SUPERCONDUCTIVITY

The ground-state energy of two electrons on a ring is calculated for t he one-dimensional Hubbard model with positive and negative on-site in teraction and for the contraction model with additive and multiplicati ve interaction terms. The hc/2e periodicity of the ground-slate energy with respect to a flux Phi threading the loop is derived. The periodi city may serve as an indication of superconductivity. The results are shown to be consistent with the Lieb-Wu solution for Phi=0 limit. In a ddition, the new states that were missing in the Lieb-Wu solution are derived. (C) 1998 American Institute of Physics.