Dependence of Δ₀ and Tc on α² (Ω) F (Ω)

Abstract

<p>We have applied the method of N-point Padé approximants to calculate the zero temperature gap edge Δ₀ from the solutions of the Eliashberg equations on the imaginary frequency axis for over thirty isotropic or 'dirty' superconductors. The same method was used in the numerical calculations of the functional derivative δΔ₀/δα² (Ω) F (Ω) for several 'dirty' superconductors. Using this functional derivative and the functional derivative of the superconducting critical temperature Tc with respect to the electron-phonon spectral function, δTc/δα² (Ω) F (Ω), we have also calculated the functional derivative δ(2Δ₀/KBTc)/ δα² (Ω) F (Ω). The universal shape of these functions should prove useful in correlating changes in the zero temperature gap edge Δ₀ and the ratio 2Δ₀/KBTc with small changes in the electron-phonon spectral function α² (Ω) F (Ω) with pressure, alloying, increasing disorder, etc.</p>