Rotational dielectric friction on a generalized charge distribution

Abstract

The dielectric friction on a solute molecule reorienting in a liquid solution is computed by modeling the solute as a rigid collection of point charges rotating within a spherical cavity in a dielectric continuum. Such a calculation on an extended charge distribution is a logical progression from existing theories, which treat only single point charges or point dipoles. It is shown how a more realistic charge distribution can change the calculated friction coefficient by several orders of magnitude, and the generalized theory is applied to rotational diffusion data for three phenoxazine dyes in dimethylsulfoxide.