Crystallization in a model glass: influence of the boundary conditions

TL;DR

This study investigates how boundary conditions affect crystallization in a model glass using molecular dynamics, revealing that boundary choices can induce or inhibit crystallization depending on system size.

Contribution

It compares the effects of cubic periodic and hyperspherical boundary conditions on crystallization in a soft-sphere glass model, highlighting boundary-induced artifacts.

Findings

Cubic boundary conditions can induce crystallization in small systems.

Hyperspherical boundary conditions inhibit crystallization even in large systems.

Finite size effects are more pronounced with hyperspherical boundaries.

Abstract

Using molecular dynamics calculations and the Voronoi tessellation, we study the evolution of the local structure of a soft-sphere glass versus temperature starting from the liquid phase at different quenching rates. This study is done for different sizes and for two different boundary conditions namely the usual cubic periodic boundary conditions and the isotropic hyperspherical boundary conditions for which the particles evolve on the surface of a hypersphere in four dimensions. Our results show that for small system sizes, crystallization can indeed be induced by the cubic boundary conditions. On the other hand we show that finite size effects are more pronounced on the hypersphere and that crystallization is artificially inhibited even for large system sizes.