Phonon-Drag Part of the Thermoelectric Power in Metals

A formula for the phonon-drag part $S_g$ of the thermoelectric power in metals is obtained by assuming that the electron scattering processes can be described by a relaxation time $\tau \left(\mathrm{k}\right)$. The formula differs from the simplest variational expression only by having extra factors of $\tau$ in numerator and denominator. The signs of the contributions of $S_g$ and the low-temperature limit are discussed.