Polydisperse hard spheres: Crystallization kinetics in small systems and role of local structure

TL;DR

This study uses molecular dynamics simulations to analyze crystallization in small polydisperse hard-sphere systems, revealing insights into the competition between crystallization and structural relaxation and evaluating local structures as order parameters.

Contribution

It demonstrates crystallization in small polydisperse systems and assesses the effectiveness of local structures as indicators of crystallization.

Findings

Crystallization occurs in small systems despite being a glass former.

Local structures provide limited additional information beyond bond order.

Crystallization and relaxation times depend on density and system size.

Abstract

We study numerically the crystallization of a hard-sphere mixture with 8\% polydispersity. Although often used as a model glass former, for small system sizes we observe crystallization in molecular dynamics simulations. This opens the possibility to study the competition between crystallization and structural relaxation of the melt, which typically is out of reach due to the disparate timescales. We quantify the dependence of relaxation and crystallization times on density and system size. For one density and system size we perform a detailed committor analysis to investigate the suitability of local structures as order parameters to describe the crystallization process. We find that local structures are strongly correlated with generic bond order and add little information to the reaction coordinate.