Models and modeling schemes for binary IV-VI glasses

Abstract

In this paper, we present and thoroughly characterize several new models of amorphous binary IV-VI glasses. We apply both a quench from the melt simulation regime and a scheme based on decoration of tetrahedral amorphous networks. We show that for certain binary IV-VI glasses (especially silica), decoration of bond-centered column VI atoms on tetrahedral amorphous networks leads with appropriate re-scaling and relaxation to highly realistic models of the IV-VI glass. In particular, the problem of freezing in too much liquid-like character seems to be significantly ameliorated. We also carry out first-principles molecular dynamics simulations to study the structural, dynamical, and electronic properties of $\mathrm{Ge}{\mathrm{Se}}_{4}$ and $\mathrm{Ge}{\mathrm{Se}}_{9}$. Good agreement with experiment is obtained for the total neutron structure factor over the entire range of $k$-space and for the electronic density of states.