Theory of Hot Electrons in Gases, Liquids, and Solids

Boltzmann's equation for electrons moving in a steady electric field is solved by the method due to Lorentz, Pidduck, and Davydov. Space-time correlations in the medium (gas, liquid, or solid) are included exactly through the use of sum rules of the Van Hove spectral function, S(K,ω). In liquids and solids the rates of momentum and energy transfer are different, the former being structure-dependent, the latter not. The error from neglect of this difference in previous treatments for solids is fortuitously canceled at low and intermediate fields by the error in the single-phonon scattering approximation also employed.