Test of the Stokes-Einstein relation in a two-dimensional Yukawa liquid

TL;DR

This study tests the validity of the Stokes-Einstein relation in a two-dimensional Yukawa liquid using molecular dynamics simulations, revealing its breakdown near the disordering transition and validation at higher temperatures.

Contribution

It provides the first detailed analysis of the Stokes-Einstein relation in a 2D Yukawa liquid, identifying regimes of validity and violation through simulations.

Findings

The Stokes-Einstein relation is violated near the disordering transition.

The relation holds at slightly higher temperatures.

Collective particle motion shows dynamical heterogeneity near transition.

Abstract

The Stokes-Einstein relation, relating the diffusion and viscosity coefficients D and eta, is tested in two dimensions. An equilibrium molecular-dynamics simulation was used with a Yukawa pair potential. Regimes are identified where motion is diffusive and D is meaningful. The Stokes-Einstein relation, D ~ kT, was found to be violated near the disordering transition; under these conditions collective particle motion exhibits dynamical heterogeneity. At slightly higher temperatures, however, the Stokes-Einstein relation is valid. These results may be testable in strongly-coupled dusty plasma experiments.