A variational principle for the acoustic attenuation of metals in the collision regime

Working within the framework of the linearized Boltzmann equation for the conduction electrons the existing theoretical treatments of acoustic attenuation in metals in the collision regime are extended to include realistic descriptions of electron-lattice scattering. In particular a variational principle for the acoustic coefficient is derived. The variational formalism also allows the inclusion of phonon drag effects in calculations of the attenuation.