An accurate Van der Waals-type equation of state for the Lennard-Jones fluid

Abstract

A new equation of state (EOS) is proposed for the Helmholtz energy F of the Lennard-Jones fluid which represents the thermodynamic properties over a wide range of temperatures and densities. The EOS is written in the form of a generalized van der Waals equation, F = FH + F^, where FH is a hard body contribution and F^ an attractive dispersion force contribution. The expression for F H is closely related to the hybrid Barker-Henderson pertubation theory. The construction of F^ is accomplished with the Setzmann-Wagner optimization procedure on the basis of virial coefficients and critically assessed computer simulation data. A comparison with the EOS of Johnson et al. shows improvement in the description of the vapor-liquid coexistence properties, the pvT data, and in peculiar, of the caloric properties. A comparison with the EOS of Kolafa and Nezbeda which appeared after the bulk of this work was finished shows still an improvement in the standard deviations of the pressure and internal energy by about 30%.

Comment on “The gas-liquid surface tension of argon: A reconciliation between experiment and simulation” [J. Chem. Phys. 140, 244710 (2014)]

“…The simulation results for the saturated liquid density by Lotfi et al 8 as well as by Potoff and Panagiotopoulos 9 generally agree with the correlation by Lotfi et al 8 within their statistical uncertainties. The results from three equations of the state by Johnson et al, 10 Kolafa and Nezbeda 11 as well as Mecke et al 12 also coincide well with the correlation by Lotfi et al 8 The simulation results by Goujon et al,…”

- Global and Local Properties of Mixtures: An Expanded Paradigm for the Study of Mixtures

“…Here we give here later developments (Wedberg 2011;Wedberg et al 2011b) than described by Wedberg et al (Wedberg et al 2010), which has less reliable approximations for the DCF tail. Figure 6.6 compares the isothermal compressibilities obtained from the method with those obtained from the EOS of Mecke et al for LJ fluids (Mecke et al 1996). At all four temperatures, our results are qualitatively consistent with the EOS, with differences in the range of 1-5%.…”

“…Its advantages of minimal computational effort and limited need for case-by-case judgment in analysis indicate its efficiency and robustness. (Mecke et al 1996) are also shown. …”

Pair correlation function integrals: Computation and use

“…3). The extrapolated h(r) integrates to ρk B T κ T = 0.055, ∼2% from the Mecke et al 60 equation of state value of 0.056. This shows that via the extrapolation method, accurate properties can be obtained from simulations of small systems, avoiding the extra computational efforts that larger systems require.…”