Long wavelength properties of electron-TO-phonon interactions in polar crystals

Theoretical analysis dealing with the interaction of electrons with the polar long-wavelength transverse optical (TO) vibrations is presented. The theory is based on the model of a polar crystal with classical potentials, which takes into account the electronic polarizability effects. A significant enhancement of the strength of the electron-TO-phonon interaction in ferroelectrics is found. A microscopic justification of this effect is given. A bridge that relates the interaction of electrons with the polar long-wavelength TO modes of the lattice vibrations to the long-range dipole-dipole interaction is established. As an application of our analysis, a new equation representing the relationship between the electron-TO-phonon interaction constant and material parameters is obtained.