Thermodynamic properties of fluids with Mie n - m potentials and application to tune effective Mie potentials for simple real fluids

Monte Carlo computer simulations have been performed to obtain the equation of state and internal energy of fluids with Mie n - m potentials, with m = 6 and n = 9,12 and 15, for different supercritical temperatures and densities covering most of the fluid phase. These data have been used to test the performance of a third order perturbation theory with the first three perturbation terms determined from computer simulation, giving rise to a very good agreement between theory and simulation. Next, the theory has been used to tune effective two-body Mie n - 6 potentials for the real fluids Ne, Ar, Kr, Xe and CH4 at supercritical temperatures for wide range of densities and pressures. It has been shown that the theory is able to accurately fit the experimental data for the energy and pressure of these fluids within the temperature and density ranges considered. This theory might be useful to obtain the equation of state and the internal energy of real molecular fluids within the context of the SAFT-VR Mie theory.