Reliable Determination of the Liquid-Vapor Critical Point by the NVT Plus Test Particle Method

抄録

We find out that the NVT plus test particle method is effective to obtain the reliable data for liquid-vapor critical point from microscopic information of interatomic potentials. The basic idea of this method is to calculate chemical potentials by test-particle insertions during canonical simulations, from which the equilibrium vapor pressure is determined. Simulations are performed at a fixed volume so that the undesirable volume fluctuations do not occur between the liquid and vapor phase. As a consequence it becomes possible to make the simulations stable even near the critical point. This is an outstanding advantage of the NVT plus test particle method when compared to the NpT plus test particle method. We apply the NVT plus test particle method to the Lennard-Jones 12-6 potential. We determine the coexistence curve far closer to the critical point than the result of the NpT plus test particle method. By applying the mixed-field finite-size scaling idea to our data, we obtain the critical temperature as T_c^*=1.3207(4), the critical density as ρ_c^*=0.316(1) and the critical pressure as p_c^*=0.1288(5). These values for T_c^*, ρ_c^* and p_c^* are the world-champion values since the error bars of these quantities are the smallest among those obtained so far.