The Lennard-Jones equation of state revisited

TLDR

The MBWR equation of state can be extended to mixtures via the van der Waals one‑fluid theory mixing rules. The study reviews existing simulation data and equations of state for the Lennard‑Jones fluid and presents new simulation results for both cut‑and‑shifted and full potentials, developing an equation of state for the cut‑and‑shifted fluid. The authors provide new parameters for the modified Benedict‑Webb‑Rubin equation, review simulation data, and generate new results for cut‑and‑shifted and full Lennard‑Jones potentials. The new equation accurately predicts vapor‑liquid equilibria, correlates pressures and internal energies from the triple point to about 4.5 times the critical temperature, and yields accurate binary mixture calculations compared with Gibbs ensemble simulations.

Abstract

We review the existing simulation data and equations of state for the Lennard-Jones (LJ) fluid, and present new simulation results for both the cut and shifted and the full LJ potential. New parameters for the modified Benedict-Webb-Rubin (MBWR) equation of state used by Nicolas, Gubbins, Streett and Tildesley are presented. In contrast to previous equations, the new equation is accurate for calculations of vapour-liquid equilibria. The equation also accurately correlates pressures and internal energies from the triple point to about 4·5 times the critical temperature over the entire fluid range. An equation of state for the cut and shifted LJ fluid is presented and compared with the simulation data of this work, and previously published Gibbs ensemble data. The MBWR equation of state can be extended to mixtures via the van der Waals one-fluid theory mixing rules. Calculations for binary fluid mixtures are found to be accurate when compared with Gibbs ensemble simulations.