We reexamine the tunneling data on A15 superconductors by performing a generalized McMillan-Rowell tunneling inversion that incorporates a nonconstant electronic density of states obtained from band-structure calculations. For ${\mathrm{Nb}}_3\mathrm{Sn},$ we find that the fit to the experimental data can be slightly improved by taking into account the sharp structure in the density of states, but it is likely that such an analysis alone is not enough to explain completely the superconducting tunneling characteristics of this material. Nevertheless, the extracted Eliashberg function displays a number of features expected to be present for the highest-quality ${\mathrm{Nb}}_3\mathrm{Sn}$ samples.

• Received 4 January 2002

DOI:https://doi.org/10.1103/PhysRevB.65.224510