Accurate vapour-liquid equilibrium calculations of simple fluids

From computer simulation data of 3D Lennard-Jones fluids, we present very simple analytical equations of pressure and chemical potential as functions of the temperature and density. By using the standard thermodynamic procedure of a liquid-vapour equilibrium; i.e. pressure and chemical potential in the gas phase to be equal to the corresponding values in the liquid phase at a given temperature, we have been able to determine the vapour-liquid coexistence curve. Despite the simplicity of our method, we obtain more precise results than those published in the literature because we use simultaneously both equalities: for pressures and for chemical potentials.