Slow dynamics in random media: Crossover from glass to localization transition

¹  Institute for Molecular Science - Okazaki 444-8585, Japan
²  Institute of Physics, University of Tsukuba - Tsukuba 305-8571, Japan

Corresponding author: kin@ims.ac.jp

Received: 30 April 2009
Accepted: 17 October 2009

Abstract

We study slow dynamics of particles moving in a matrix of immobile obstacles using molecular-dynamics simulations. The glass transition point decreases drastically as the obstacle density increases. At higher obstacle densities, the dynamics of mobile particles changes qualitatively from glass-like to a Lorentz-gas-like relaxation. This crossover is studied by density correlation functions, nonergodic parameters, mean square displacement, and nonlinear dynamic susceptibility. Our finding is qualitatively consistent with the results of recent numerical and theoretical studies on various spatially heterogeneous systems. Furthermore, we show that slow dynamics is surprisingly rich and sensitive to obstacle configurations. Especially, the reentrant transition is observed for a particular configuration, although its origin is not directly linked to the similar prediction based on the mode-coupling theory.