Revealing the Medium-Range Structure of Glassy Silica using Force-Enhanced Atomic Refinement

The medium-range order structure of silicate glasses remains poorly known as it is not directly visible from conventional experiments. In turn, although atomistic simulations offer a direct access to the structure of glasses, they face several limitations, e.g., extremely high cooling rates. Here, we adopt the force-enhanced atomic refinement (FEAR) method to overcome these limitations and reveal the atomic structure of glassy silica, both at the short- and medium-range length scales. We find that FEAR yields a glass structure that simultaneously exhibits higher thermodynamic stability and enhanced agreement with experimental structure data as compared with molecular dynamics and reverse Monte Carlo simulations. Overall, we show that the increased stability enabled by FEAR primarily arises from the fact that the generated atomic configuration exhibits a more ordered medium-range structure and a lower fraction of unstable small silicate rings.