Rotational correlation and dynamic heterogeneity in a kinetically constrained lattice gas

TL;DR

This paper investigates how rotational and translational motions behave differently in a lattice gas model nearing glass transition, revealing decoupling and heterogeneity in dynamics.

Contribution

It introduces a model with coupled rotational and translational degrees of freedom and analyzes their dynamic heterogeneity and decoupling near glassy states.

Findings

Rotational diffusion tracks structural relaxation time with increasing density.

Translational diffusion shows strong decoupling from structural relaxation.

Distributions of exchange and persistence times reveal heterogeneity in dynamics.

Abstract

We study dynamical heterogeneity and glassy dynamics in a kinetically constrained lattice gas model which has both translational and rotational degrees of freedom. We find that the rotational diffusion constant tracks the structural relaxation time as density is increased whereas the translational diffusion constant exhibits a strong decoupling. We investigate distributions of exchange and persistence times for both the rotational and translational degrees of freedom and compare our results on the distributions of rotational exchange times to recent single molecule studies.