# Dynamics of dense hard sphere colloidal systems: a numerical analysis

## TL;DR

This paper tests the applicability of Record Dynamics to dense hard sphere colloidal systems through molecular dynamics simulations, confirming key theoretical predictions and analyzing particle displacements and intermittent events.

## Contribution

It demonstrates that Record Dynamics accurately describes aging and cage-breaking phenomena in dense colloidal suspensions, providing quantitative measures and linking to dynamical barriers.

## Key findings

- Reproduces logarithmic diffusion and energy decay.
- Identifies cage sizes and particle displacements at cage breakings.
- Shows quakes form a log-Poisson process, independent and Poisson distributed.

## Abstract

The applicability to dense hard sphere colloidal suspensions of a general coarse-graining approach called Record Dynamics (RD) is tested by extensive molecular dynamics simulations. We reproduce known results as logarithmic diffusion and the logarithmic decay of the average potential energy per particle. We provide quantitative measures for the cage size and identify the displacements of single particles corresponding to cage breakings. We then partition the system into spatial domains. Within each domain, a subset of intermittent events called quakes is shown to constitute a log-Poisson process, as predicted by Record Dynamics. Specifically, these events are shown to be statistically independent and Poisson distributed with an average depending on the logarithm of time. Finally, we discuss the nature of the dynamical barriers surmounted by quakes and link RD to the phenomenology of aging hard sphere colloids.