A distance-based structural descriptor for the glass transition across diverse liquids

Abstract The glass transition—characterized by orders-of-magnitude slowing of dynamics alongside remarkably subtle structural changes—represents one of condensed matter physics’ most enduring mysteries. A key challenge has been the lack of a metric that can characterize structural changes during the glass transition. Guided by the observation that viscosities converge to ~10 12 Pa·s near the glass transition for most systems while universally approaching ~10 −4 Pa·s for high-temperature liquids, we introduce a configurational order parameter, D, representing the distance of the configuration between glassy and liquid reference states. Through molecular dynamics simulations spanning metallic glasses, oxide glasses, and binary Lennard-Jones mixtures, we demonstrate that D is a sensitive structural indicator of vitrification in amorphous materials.