EFFECT OF PAIR FLUCTUATIONS ON THE ELECTRONIC-PROPERTIES OF THE NEGATIVE HUBBARD-MODEL

Based on the fact that high-T-c superconductors exhibit strong fluctua tions, we have allowed the presence of pair fluctuations in the framew ork of the T-matrix formation using the 2-D negative Hubbard model for temperatures above and below T-c. Our equations are fully self-consis tent. For T greater than or equal to T-c the electronic properties cha nge drastically with respect to BCS treatment, namely, there is a pseu dogap around the chemical potential in the density of states, and the spectral function, A(k,omega), vs. omega exhibits a double peak struct ure which is related to the appearance of this pseudogap. For T less t han or equal to T-c, we have generalized the formalism in order to inc lude the order parameter.