Nonlinear dielectric relaxation of polar liquids

TL;DR

This study uses molecular dynamics simulations of water models to confirm the Kivelson-Madden equation and investigates how electric fields influence dielectric relaxation, emphasizing single-particle rotational effects.

Contribution

It validates the Kivelson-Madden relation for water and highlights the dominant role of single-particle rotations in nonlinear dielectric relaxation.

Findings

The Kivelson-Madden equation holds for water models.

Electric fields mainly slow down single-particle rotations.

Alteration of the Kirkwood factor by the field is negligible.

Abstract

Molecular dynamics of two water models, SPC/E and TIP3P, at a number of temperatures is used to test the Kivelson-Madden equation connecting single-particle and collective dielectric relaxation times through the Kirkwood factor. The relation is confirmed by simulations and used to estimate the nonlinear effect of the electric field on the dielectric relaxation time. We show that the main effect of the field comes through slowing down of the single-particle rotational dynamics and the relative contribution of the field-induced alteration of the Kirkwood factor is insignificant for water. Theories of nonlinear dielectric relaxation need to mostly account for the effect of the field on rotations of a single dipole in a polar liquid.