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

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