The Gibbs ensemble Monte Carlo (GEMC) method is a versatile approach for the prediction of fluid phase equilibria from particle-based simulations. For a one-component system, a GEMC simulation utilises two separate simulation boxes for the vapour and the liquid phases and a significant fraction of the computational effort is expended on special trial moves that transfer (swap) particles and exchange volume between the two boxes. The user needs to specify the frequency of swap and volume moves and the overall volume that controls the phase ratio. In this study, the efficiency of GEMC simulation protocols that yield three different frequencies of accepted swap and volume moves and three different phase ratios is assessed for the computation of the saturated vapour pressure and liquid density of n-octane and water at three reduced temperatures. Differences in the simulation efficiency of up to an order of magnitude are observed, and recommendations are made for suitable GEMC simulation protocols.
Bibliographical noteFunding Information:
Financial support from the Abu Dhabi–Minnesota Institute for Research Excellence (ADMIRE), a partnership between the Petroleum Institute of Abu Dhabi and the Department of Chemical Engineering and Materials Science of the University of Minnesota, and from the National Science Foundation (CHE-1159837), is gratefully acknowledged. Part of the computer resources was provided by the Minnesota Supercomputing Institute.
- Gibbs ensemble
- Monte Carlo simulation
- vapour-liquid equilibria
- water; n-octane