A T(c) formula and the isotope effect for strong-coupled superconductors

In this study we obtain analytically the transition temperature T(c) which is similar to the one due to Allen and Dynes, and the isotope effect. Using the Eliashberg theory that includes both the electron-electron and electron-phonon interactions in superconductors, we calculate the transition temperature T(c) and the coefficient alpha of the isotope effect for a group of superconductors under study