The role of translational diffusion in the polarization relaxation in dense polar liquids

Abstract

The role of translational diffusion in the dynamics of polar solvation is investigated by using a Smoluchowski-Vlasov equation. It is shown that translational diffusion plays an important role in solvent polarization relaxation at intermediate wave numbers ( k≈2π/σ, σ is the solvent molecular diameter) and that the microscopic structure of the polar liquid must be considered in order to understand the role of translational diffusion. The translational contribution to polarization relaxation depends on the relative sizes of the solute and the solvent molecules, on the relative values of translational and rotational diffusion coefficients and also on the order of the multipole that gives the solute charge distribution.