Extension of Molecular Exchange Monte Carlo for the Prediction of Liquid–Liquid Equilibria in Gibbs Ensemble Monte Carlo Simulations

The Molecular Exchange Monte Carlo (MEMC) algorithm is extended to support the calculation of liquid-liquid equilibria with Gibbs ensemble Monte Carlo (GEMC). The utility of the method is demonstrated through the application of constant-pressure GEMC simulations, using the Transferable Potentials for Phase Equilibria, to predict liquid-liquid coexistence curves for mixtures of perfluoroalkanes + alkanes and dimethyl ether + water. Good qualitative agreement is achieved between the predictions of the simulation and experiment; however, improvements to the intermolecular potentials used are required to achieve quantitative accuracy. Relative acceptance rates for molecule transfers up to 50 times greater than those obtained with standard configurational-bias Monte Carlo are obtained.