The glass transition in a model silica glass: evolution of the local structure

TL;DR

This study uses molecular dynamics and Voronoi tessellation to analyze how local structure in silica glass evolves with temperature, revealing structural freezing at the glass transition linked to geometrical frustration.

Contribution

It provides new insights into the structural changes and geometric frustration in silica glass during cooling, using detailed Voronoi analysis.

Findings

Standard deviation of cell volumes decreases with temperature

Structural freezing occurs at the glass transition

Geometrical frustration influences amorphous structure

Abstract

We use molecular dynamics simulations and the Voronoi tessellation to study the geometrical modifications as a function of temperature in a model silica glass. The standard deviation of the cell volumes, which is a measure of the local density fluctuations, decreases with decreasing temperature, as if it would like to vanish at zero temperature. This evolution towards an ordered state is frozen out at the glass transition and consequently an amorphous sample is obtained at low temperature. This structural freezing following upon the glass transition is noticeable in all the other geometric characteristics of the Voronoi cells and a possible interpretation in terms of geometrical frustration is proposed.