Many-body effects in some thermodynamic properties of supercritical CO2, CO2–Ar, and CO2–CH4 using HFD-like potentials from molecular dynamics simulation

Molecular dynamics simulation has been performed to obtain the pressure and self-diffusion coefficient of supercritical carbon dioxide using a two-body HFD (Hartree–Fock dispersion)-like potential determined via the inversion of reduced viscosity collision integrals at zero pressure. We have also obtained pressures of CO2–Ar and CO2–CH4 fluid mixtures at constant temperatures at different densities using new accurate two-body HFD-like potential functions. To take many-body forces into account, the three-body potentials of Hauschild and Prausnitz [27], Wang and Sadus [30] and [38], Oakley et al. [3], and Guzman et al. [33] have been used with the two-body potentials. The significance of this work is that the modified many-body potential of Hauschild and Prausnitz (extended as a function of density, temperature, and molar fraction) has been used with the two-body HFD-like potentials of CO2, CO2–Ar, and CO2–CH4 systems to improve the prediction of the pressure values without requiring an expensive three-body calculation. The results are in good agreement with experimental values.

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► MD simulation performed to obtain pressures of supercritical CO2, CO2–Ar, and CO2–CH4.
► Four simple three-body potentials used to improve the prediction of the results.
► We have also simulated self-diffusion of CO2 in good agreement with the experiment.