A new simulation method for the determination of phase equilibria in mixtures in the grand canonical ensemble

A grand canonical Monte Carlo (GCMC) simulation method is presented for the determination of the phase equilibria of mixtures. The coexistence is deri ved by expanding the pressure into a Taylor series as a function of the tem perature and the chemical potentials that are the independent intensive var iables of the grand canonical ensemble. The coefficients of the Taylor seri es can be calculated from ensemble averages and fluctuation formulae that a re obtained from GCMC simulations in both phases. The method is able to pro duce the equilibrium data in a certain domain of the. (T, p) plane from two GCMC simulations. The vapour-liquid equilibrium results obtained for a Len nard-Jones mixture agree well with the corresponding Gibbs ensemble Monte C arlo data.