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

TL;DR

This study investigates how increasing obstacle density in a medium causes a transition from glass-like to Lorentz-gas-like particle dynamics, revealing complex behaviors and reentrant transitions influenced by obstacle configurations.

Contribution

It demonstrates the qualitative change in particle dynamics with obstacle density and highlights the sensitivity of slow dynamics to obstacle arrangements, including reentrant transitions.

Findings

Glass transition point decreases with obstacle density

Dynamics change from glass-like to Lorentz-gas-like at high densities

Reentrant transition observed for specific obstacle configurations

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 mode-coupling theory.