Spectral shape dependence in the very strong coupling regime of Eliashberg theory

The effect of α2F(ω) shape dependence on several physical properties of superconductors is studied at various values of the strong coupling index Tc/ω1n. The authors results indicate that the degree of shape dependence of each property is sensitive to the value of Tc/ωin. Generally, for the region they examine, 0.25 ≤ Tc/ω1n ≤ 1.3, the dependence on shape is found to be higher than in the conventional strong coupling regime Tc/ω1n approx-lt 0.2. However, with the exception of the mass enhancement parameter λ, the amount of shape dependence does not increase steadily with Tc/ω1n and there appears to be regions of maximum shape sensitivity