SUPERCONDUCTIVITY AND RANDOM DISORDER IN THE NARROW AND WIDE-BAND LIMIT

We investigate the effects of a finite electronic bandwidth in a disor dered superconductor by considering the current tight binding Anderson model of disorder and a mean field BCS interaction. A general relatio n, between the transition temperature T(c) and the disorder averaged s pectral density associated with the electron propagator between neighb oring lattice sites is found which enables us to predict superconducti vity in the disorder induced localized state. A reasonable interpolati on, between weak and strong disorder, is investigated and it predicts a maximum bandwidth where superconductivity is destroyed. In this case , T(c) as a function of the disorder is shown for a few values of the hopping constant. A brief discussion of the model validity range and i ts applications to disordered granular superconductors is presented.