Vibrational signature of broken chemical order in a GeS2 glass: a molecular dynamics simulation

TL;DR

This study uses molecular dynamics simulations to analyze how broken chemical order in GeS2 glass affects its vibrational properties, revealing specific atomic modes and structural changes consistent with experimental observations.

Contribution

It provides new insights into the vibrational modes associated with broken chemical order and structural transformations in GeS2 glass through detailed simulation analysis.

Findings

Homopolar bonds and their vibrational frequencies match experimental data.

Localized S-S vibrational modes explain specific Raman peaks.

Conversion of ring sizes during glass formation affects vibrational signatures.

Abstract

Using density functional molecular dynamics simulations, we analyze the broken chemical order in a GeS$_2$ glass and its impact on the dynamical properties of the glass through the in-depth study of the vibrational eigenvectors. We find homopolar bonds and the frequencies of the corresponding modes are in agreement with experimental data. Localized S-S modes and 3-fold coordinated sulfur atoms are found to be at the origin of specific Raman peaks whose origin was not previously clear. Through the ring size statistics we find, during the glass formation, a conversion of 3-membered rings into larger units but also into 2-membered rings whose vibrational signature is in agreement with experiments.