ABSTRACT
This chapter examines a number of properties of superconductors for which weak-coupling calculations has proved successful. The bcs weak-coupling thermodynamic predictions are generally successful for conventional superconductors having values of NV. It is sometimes useful to consider wavepackets corresponding to localized excitations, made up of a linear combination of electron-like excitation states having a small range of k vectors. The scattering rates for electron-like and hole-like excitations in superconductors are different from those in the corresponding normal metal, for several reasons. The rates are governed by Fermi's golden rule in the usual way, and are therefore proportional to the square of the effective matrix element and to the final density of states for excitations. In very pure material or when the electron-phonon coupling is strong the electrons are scattered mainly by the phonons. Longitudinal acoustic waves of wavevector q and frequency Ω are absorbed by scattering electron-like excitations, with conservation of energy and wavevector.
