An EOS for the Lennard-Jones fluid: A virial expansion approach

A large number (>30 000) of Monte Carlo simulations in range of 0.002–1.41 ρ* and T* ≤ 25 (* for reduced, dimensionless) was performed, producing a dense grid of state points for the internal energy U* and pressure p*. The dense grid in ρ* allows the direct integration to obtain the Helmholtz free energy F*. The results in U*, p*, and F* were used to fit an equations of state (EOS) for the Lennard-Jones fluid using the virial thermal coefficients B2–B6 taken from the literature and additional empirical coefficients (C7-C16), which correct the errors due to nonconverging behavior of virial thermal coefficients. Those additional coefficients have the same mathematical form as the virial thermal coefficients. The EOS allows an extrapolation to extreme conditions above T* > 100 and ρ* > 2.