Gibbs ensemble Monte Carlo
Phase separation is one of the topics to which simulation techniques are increasingly applied. Different procedures are available for this purpose. For the particular case of chain systems, one can employ simulations in the semi-grand canonical ensemble, histogram reweighting, or characterization of the spinodal curve from the study of computed collective scattering function. The Gibbs ensemble Monte Carlo method has been specifically designed to characterize phase transitions. It was mainly developed by Panagiotopoulos   to avoid the problem of finite size interfacial effects. In this method, an NVT (or NpT) ensemble containing two (or more) species is divided into two (or more) boxes. In addition to the usual particle moves in each one of the boxes, the algorithm includes moves steps to change the volume and composition of the boxes at mechanical and chemical equilibrium. Transferring a chain molecule from a box to the other requires the use of an efficient method to insert chains. The configurational bias method is specially recommended for this purpose.
- Athanassios Panagiotopoulos "Direct determination of phase coexistence properties of fluids by Monte Carlo simulation in a new ensemble", Molecular Physics 61 pp. 813-826 (1987)
- A. Z. Panagiotopoulos, N. Quirke, M. Stapleton and D. J. Tildesley "Phase equilibria by simulation in the Gibbs ensemble: Alternative derivation, generalization and application to mixture and membrane equilibria", Molecular Physics 61 pp. 527-545 (1988)
- Related reading
- Mohammadhasan Dinpajooh, Peng Bai, Douglas A. Allan and J. Ilja Siepmann "Accurate and precise determination of critical properties from Gibbs ensemble Monte Carlo simulations", Journal of Chemical Physics 143 114113 (2015)