Dynamical Exchanges in Facilitated Models of Supercooled liquids

TL;DR

This study analyzes dynamical exchange events in facilitated models of supercooled liquids across different dimensions, revealing how exchange times depend on temperature, model parameters, and dimension, with implications for understanding glassy dynamics.

Contribution

It provides a detailed statistical analysis of exchange and persistence times in facilitated models, highlighting the sensitivity of exchange time distributions to model parameters and dimensions, and establishing Arrhenius behavior for mean exchange times.

Findings

Exchange time distributions are sensitive to model parameters and dimensions.

Mean exchange times follow Arrhenius behavior, scaling as c^{-2}.

Different dynamical exchange processes are characterized from trajectories.

Abstract

We investigate statistics of dynamical exchange events in coarse--grained models of supercooled liquids in spatial dimensions $d=1$, 2, and 3. The models, based upon the concept of dynamical facilitation, capture generic features of statistics of exchange times and persistence times. Here, distributions for both times are related, and calculated for cases of strong and fragile glass formers over a range of temperatures. Exchange time distributions are shown to be particularly sensitive to the model parameters and dimensions, and exhibit more structured and richer behavior than persistence time distributions. Mean exchange times are shown to be Arrhenius, regardless of models and spatial dimensions. Specifically, $<t_{\rm x}> \sim c^{-2}$, with $c$ being the excitation concentration. Different dynamical exchange processes are identified and characterized from the underlying trajectories. We discuss experimental possibilities to test some of our theoretical findings.