Electron‐Phonon Interaction and Superconductivity in Metals

Abstract

Abstract A first principle derivation, in terms of electron‐ion pseudopotential and the phonon spectrum, is presented for the electron‐phonon coupling constant λ. The phonon parameters, needed in the calculation, are characterised by a single average square frequency, which is evaluated after Allen and Cohen. The computed λ, along with the values of Coulomb pseudopotential μ* and Debye temperature θ D , leads to an over‐all satisfactory result for the transition temperature and isotope effect exponent according to the formulation developed by McMillan. Further, the calculations demonstrate unambiguously the existence of Matthias regularities.