Theory for dirty superconductors. II. McMillan solution andTcdegradation

For a recent strong-coupling theory for dirty superconductors, a solution for $T_c$ of the McMillan type is obtained, which still contains complete disorder renormalizations of both anomalous and normal self-energies. All disorder effects leading to diffusion enhancement of vertices are calculated. The resulting $T_c$ formula gives good account of the observed $T_c$ degradation in high-$T_c$ materials. A detailed discussion of the approximations used and of the relation to previous approaches is given.