Aging in a Laponite colloidal suspension: A Brownian dynamics simulation study

TL;DR

This study uses Brownian dynamics simulations to explore the aging and out-of-equilibrium behavior of a colloidal suspension modeled after Laponite, revealing complex dynamics and the potential formation of a Wigner glass state.

Contribution

First simulation to analyze out-of-equilibrium aging dynamics in a Laponite-like colloidal suspension, focusing on wave-vector and waiting time dependence of density fluctuations.

Findings

Confirmation of complex aging dynamics in the model

Evidence suggesting formation of a Wigner glass state

Analysis of single-particle and collective density fluctuations

Abstract

We report Brownian dynamics simulation of the out-of-equilibrium dynamics (aging) in a colloidal suspension composed of rigid charged disks, one possible model for Laponite, a synthetic clay deeply investigated in the last few years by means of various experimental techniques. At variance with previous numerical investigations, mainly focusing on static structure and equilibrium dynamics, we explore the out-of-equilibrium aging dynamics. We analyze the wave-vector and waiting time dependence of the dynamics, focusing on the single-particle and collective density fluctuations (intermediate scattering functions), the mean squared displacement and the rotational dynamics. Our findings confirm the complexity of the out-of-equilibrium dynamical behavior of this class of colloidal suspensions and suggest that an arrested disordered state driven by a repulsive Yukawa potential, i.e., a Wigner glass can be observed in this model.