Understanding the Dynamics of Glass-forming Liquids with Random Pinning within the Random First Order Transition Theory

TL;DR

This study uses computer simulations to explore how randomly freezing particles in glass-forming liquids affects their dynamics, supporting RFOT theory and revealing how fragility decreases with increased pinning.

Contribution

It introduces a scaling framework that links pinning-induced changes in relaxation dynamics to RFOT static length scales, advancing understanding of glass fragility.

Findings

Relaxation time behavior aligns with RFOT predictions.

Fragility decreases significantly with increased pinning.

Scaling description successfully captures simulation data.

Abstract

Extensive computer simulations are performed for a few model glass-forming liquids in both two and three dimensions to study their dynamics when a randomly chosen fraction of particles are frozen in their equilibrium positions. For all the studied systems, we find that the temperature-dependence of the $\alpha$ relaxation time extracted from an overlap function related to the self part of the density autocorrelation function can be explained within the framework of the Random First Order Transition (RFOT) theory of the glass transition. We propose a scaling description to rationalize the simulation results and show that our data for the $\alpha$ relaxation time for all temperatures and pin concentrations are consistent with this description. We find that the fragility parameter obtained from fits of the temperature dependence of the $\alpha$ relaxation time to the Vogel-Fulcher-Tammann (VFT) form decreases by almost an order of magnitude as the pin concentration is increased from zero. Our scaling description relates the fragility parameter to the static length scale of RFOT and thus provides a physical understanding of fragility within the framework of the RFOT theory. Implications of these findings for the values of the exponents appearing in the RFOT theory are discussed.