Interference effects between electron-phonon and electron-impurity scattering in the low temperature electrical resistivity of metals

Caplin, Napoli and Sherrington (1973) have stated that the normally accepted condition for the independence of electron-phonon and electron-impurity scattering, ql>>1, is wrong and a much stronger condition is needed. It is shown that the normally accepted condition is in fact correct, and that the condition derived by Caplin et al. does not apply for their discussion of electrical resistivity at low temperatures.