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.