Self-consistent molecular theory of orientational relaxation and dielectric friction in a dense dipolar liquid

Abstract

A self-consistent molecular theory of orientational relaxation and dielectric friction is presented. It is shown that both the translational and the rotational dielectric frictions on a dipolar solute molecule are coupled to each other. The respective frictions can be obtained from a set of coupled non-linear equations which are presented. A new result of this work is the demonstration that the observed much reduced friction for the collective rotation compared to the single particle friction can be explained in terms of participation of the self-motion of the dipolar solute in the former. It is also shown that the orientational caging of a dipolar solute may contribute even 15-20 % of the total translational dielectric friction. This seems to be in agreement with recent computer simulation results.