Computer simulation of low-energy excitations in amorphous silicon with voids

TL;DR

This study uses molecular dynamics simulations to analyze low-energy vibrational modes in amorphous silicon with voids, revealing localized excitations and their classifications related to voids and strained regions.

Contribution

It introduces a detailed computational approach to identify and classify low-energy vibrational modes in amorphous silicon containing voids, highlighting their localized nature.

Findings

Localized low-energy vibrational excitations are present in models with voids.

Vibrational modes can be classified as void-associated or mixed modes.

Complex structure of excitations suggests interaction between voids and strained regions.

Abstract

We use empirical molecular dynamics technique to study the low-energy vibrations in a large 4096 atom model for pure amorphous silicon and a set of models with voids of different size based on it. Numerical vibrational eigenvalues and eigenvectors for our models are obtained by exact diagonalization of their dynamical matrices. Our calculations show that localized low-energy vibrational excitations of rather complex structure are present in amorphous silicon models with voids. According to their spatial localization patterns we make an attempt to classify these excitations as modes associated with the void and "mixed" modes associated with the interaction of the void with strained regions of silicon network.