Self-diffusion in sheared colloidal suspensions: violation of fluctuation-dissipation relation

TL;DR

This paper demonstrates that in sheared colloidal suspensions, the fluctuation-dissipation theorem for self-diffusion is violated, and introduces a new method to measure this violation through Brownian Dynamics simulations.

Contribution

It derives mode-coupling expressions for the tagged particle friction tensor and proposes a way to quantify the violation of fluctuation-dissipation relation under shear.

Findings

Fluctuation-dissipation theorem is violated in sheared colloidal suspensions.

A new measurement method for this violation is proposed.

Derived mode-coupling expressions for particle friction and effective temperature.

Abstract

Using memory-function formalism we show that in sheared colloidal suspensions the fluctuation-dissipation theorem for self-diffusion, i.e. Einstein's relation between self-diffusion and mobility tensors, is violated and propose a new way to measure this violation in Brownian Dynamics simulations. We derive mode-coupling expressions for the tagged particle friction tensor and for an effective, shear-rate dependent temperature.