Electron—Phonon Interaction

Abstract

Based on the Born-Oppenheimer approximation (Chap. 2) the dynamics of the heavy and light constituents of a solid, the ions and the electrons, respectively, have been presented in the previous chapters as those of independent systems. For the lattice dynamics (Chap. 3) is was important only to know, that the electrons contribute to the binding forces which determine the dynamical matrix, while for the electrons (Chaps. 4–7), their band structure or spin excitations, the chemical nature of the ions was the origin of material specific properties but their positions were kept fixed in the periodic configuration of the lattice. Releasing the Born-Oppenheimer approximation enables the two subsystems to communicate with each other by exchanging energy. This leads to a variety of effects, which are not restricted to solids but are found in all types of condensed matter including macromolecular systems in chemistry and biology.