A NEW SIMULATION METHOD FOR THE DETERMINATION OF THE VAPOR-LIQUID-EQUILIBRIA IN THE GRAND-CANONICAL ENSEMBLE

A new simulation method is introduced for the determination of the vap our-liquid phase separation of pure fluids in the grand canonical ense mble. It is based on the third-order Taylor series of the pressure wit h respect to the reciprocal temperature term (beta = 1/kT) and the con figurational chemical potential. The coefficients of the series can be obtained via fluctuation formulae by performing grand canonical Monte Carlo simulations at suitably prescribed vapour- and liquid-phase raw points, The method was tested on the Lennard-Jones fluid. Though ther e is some inefficiency in the calculation of the pressure on the liqui d side, the algorithm enables the derivation of the equilibrium data w ith satisfactory accuracy.