Localized potential method in the theory of electron-phonon interaction

The matrix element of the electron-phonon interaction in metals and semiconductors is expressed by the matrix elements of the potentials induced by displacement of individual nuclei (localized potentials), in Bloch and Wannier representations. The formalism of Mitra (1969) is generalized to non-Bravais crystal lattices, and the rigid-ion approximation is avoided. Sum rules for the matrix elements of localized potentials are derived.