Super-Arrhenius temperature dependent viscosity due to liquid-liquid phase separation in the super-cooled Kob-Andersen model

Abstract

In this study, a recently introduced order parameter called the weighted coordination number (WCN) was used to investigate the liquid-liquid (LL) phase separation, indicating temperature-dependent coarsening of the LL interface as a possible mechanism for the glass transition. A well-established glass-forming Kob-Andersen binary Lennard-Jones system was used in this study. The gas-liquid binodal line was reconstructed using WCNs, and the same approach was extended to study the liquid-liquid binodal line. Systems of various densities are instantaneously quenched from high to low temperatures where liquid-liquid separation is observed. The densities and composition of each liquid state were used to verify the level rule, along with the density and pressure profiles, demonstrating the local equilibrium of liquid-liquid phase separation. The transition from the liquid-liquid phase separation in the supercooled region to the glass transition region was modeled by adopting a Markov Network Model to estimate the temperature-dependent viscosity using liquid-liquid interfacial information from the classification.