The role of thermostats in simulations of jamming

The onset of jamming is a physical phenomenon that occurs in many different systems on a multitude of different length scales, from granular particles in silos to vehicles in traffic. However the underlying nature of jamming, and the physical mechanisms which lead to its onset, remain a topic of intense debate. In this work, we perform non-equilibrium molecular dynamics (MD) simulations of sheared colloidal suspensions where different definitions of the system temperature (e.g., kinetic or configurational temperature) are thermostatted [1,2]. This thermostat modifies the equation of motion of the particles in the system, mimicking the influence of the interstitial fluid. We examine the influence of the choice of temperature on the jamming behaviour in the system. The aim of this work is to create a thermostat which adequately reproduces the hydrodynamic interactions in a densely packed colloidal suspension. We study jamming statistics from the simulation such as distributions in pressure and viscosity as well as correlation functions of the configurational temperature and compare with similar statistics from an experimental sheared colloidal suspension. [1] Lue, L. et al. "Configurational Thermostats for Molecular Systems", Molecular Physics (100), p2387-2395, 2002. [2] Rugh, H.H. "Dynamical Approach to Temperature", Phys Rev Lett (78), p772-774, 1997