Spatially heterogeneous dynamics and dynamic facilitation in a model of viscous silica

TL;DR

This study uses molecular dynamics simulations to reveal that viscous silica exhibits spatially heterogeneous relaxation dynamics and that high mobility regions facilitate further particle movement, supporting dynamic facilitation theories.

Contribution

It demonstrates the spatial heterogeneity of relaxation dynamics in viscous silica and confirms the role of dynamic facilitation in its structural relaxation.

Findings

Relaxation dynamics are spatially heterogeneous.

High mobility propagates continuously through the melt.

Supports the concept of dynamic facilitation in viscous silica.

Abstract

Performing molecular dynamics simulations, we find that the structural relaxation dynamics of viscous silica, the prototype of a strong glass former, are spatially heterogeneous and cannot be understood as a statistical bond breaking process. Further, we show that high particle mobility predominantly propagates continuously through the melt, supporting the concept of dynamic facilitation emphasized in recent theoretical work.