Improved Estimates of the Critical Point Constants for Large n-Alkanes Using Gibbs Ensemble Monte Carlo Simulations

Abstract

In this work, we present improved estimates of the critical temperature (Tc), critical density (ρc), critical pressure (Pc), and critical compressibility factor (Zc) for n-alkanes with chain lengths as large as C48. These are obtained for several different force field models with Gibbs ensemble Monte Carlo simulations. We implement a recently proposed data analysis method designed to reduce the uncertainty in Tc, ρc, Pc, and Zc when predicted with molecular simulation. The results show a large reduction in the uncertainties compared to the simulation literature with the greatest reduction found for ρc, Pc, and Zc. Previously, even the most computationally intensive molecular simulation studies have not been able to elucidate the n-alkane Pc trend with respect to larger carbon numbers. The results of this study are significant because the uncertainty in Pc is small enough to discern between conflicting experimental data sets and prediction models for large n-alkanes. Furthermore, the results for Tc resolve...