Theory of Multiphonon Absorption: A Review

Abstract

The theories of multiphonon absorption in ionic insulators for frequencies several times the reststrahl frequency are reviewed. The physical properties of the solid, anharmonic potential and nonlinear dipole moment, which are responsible for multiphonon absorption are discussed. The rather large number of theoretical calculations are classified with an attempt to highlight simularities and basic differences between the theoretical techniques used and the physics contained in or implied by the calculations. Finally, a result connecting the analyticity of the potential and dipole moment operator, and the behavior of ε_2(ω) at high frequencies is presented.

Additional details