Coexistence Densities of Methane and Propane by Canonical Molecular Dynamics and Gibbs Ensemble Monte Carlo Simulations

We present preliminary canonical molecular dynamics (MD) and Gibbs ensemble Monte Carlo (GEMC) results for the vapour–liquid orthobaric densities of methane and propane. Computational advantages and drawbacks of both simulation methods are discussed and future work is outlined on the application of these techniques to the calculation of transport and interfacial properties. n-Alkanes are described through the TraPPE-UA force field. We study the effect of the truncation of interactions in the Lennard–Jones potential on the accuracy of the orthobaric liquid densities for these inhomogeneous systems along the phase diagram. We observed that a cutoff of at least 5.5 times the Lennard–Jones diameter is needed to obtain accurate results for saturated liquid densities.