Large well-relaxed models of vitreous silica, coordination numbers and entropy

TL;DR

This paper introduces a Monte Carlo simulation method for creating large, well-relaxed vitreous silica networks that align well with experimental data and provides insights into their structure and entropy.

Contribution

The study presents a new Monte Carlo approach for simulating vitreous silica, achieving larger, more accurate networks with improved structural properties over previous methods.

Findings

Networks show smaller bond-angle variations and fewer defects.

Total correlation functions match neutron scattering data.

Gaussian fitting can lead to incorrect coordination number estimates.

Abstract

A Monte Carlo method is presented for the simulation of vitreous silica. Well-relaxed networks of vitreous silica are generated containing up to 300,000 atoms. The resulting networks, quenched under the BKS potential, display smaller bond-angle variations and lower defect concentrations, as compared to networks generated with molecular dynamics. The total correlation functions T(r) of our networks are in excellent agreement with neutron scattering data, provided that thermal effects and the maximum inverse wavelength used in the experiment are included in the comparison. A procedure commonly used in experiments to obtain coordination numbers from scattering data is to fit peaks in rT(r) with a gaussian. We show that this procedure can easily produce incorrect results. Finally, we estimate the configurational entropy of vitreous silica.