DETERMINATION OF VAPOR-LIQUID-EQUILIBRIUM USING CAVITY-BIASED GRAND-CANONICAL MONTE-CARLO METHOD

In a previous paper a new simulation method was introduced for the det ermination of vapour-liquid equilibrium (VLE) of pure fluids in the gr and canonical ensemble (Boda, D., Liszi, J., and Szalai, I., 1996, Che m. Phys. Lett., 256, 474). Its basic idea is the extrapolation of the pressure in the directions of reciprocal temperature and configuration al chemical potential via third-order Taylor series expansion: p(beta, mu). The coefficients of the series can be obtained from fluctuation f ormulae by performing grand canonical Monte Carlo (GC MC) simulations on both vapour and liquid sides. It was found that the main shortcomin g of the method originates from the inaccurate calculation of the pres sure on liquid side because of the slow convergence of the original GC MC simulation used. It is now shown that the application of the cavit y-biased GC MC method of Mezei on the liquid side can overcome this di fficulty. The linked-cell method to fasten the cavity-searching algori thm is proposed. The results of test calculations for the Lennard-Jone s system show excellent agreement with those obtained by the NpT plus test particle method. The method can be implemented for the determinat ion of phase separation in mixtures in a straightforward manner.