(500f) Critical and Phase-Equilibrium Properties of Different Force-Field Models for 1-Propanol Using Two-Phase Molecular Dynamics Simulations

Two-phase molecular Dynamics (MD) simulations employing a Monte Carlo (MC) volume sampling method were performed on models representing 1-Propanol at temperatures approaching the critical temperature. Two intermolecular potential models were used to obtain the bimodal vapor-liquid curve at elevated temperatures to within about 10 degrees of the critical temperature. These data were used in conjunction with the law of rectilinear diameters and the known critical exponent of two-phase density difference to obtain the critical temperature and density for the two model fluids. An all-atom, site-site pair potential model developed solely from ab initio pair interactions and fitted to a modified Morse potential is tested for the first time and compared to the results obtained using the Transferable Potential for Phase Equilibria United Atom (TraPPE-UA) model which has been tuned with phase equilibria data. Results obtained for critical temperature, critical densities, and the bulk vapor and liquid densities for the two models will be compared to experimental data. The two-phase MD method with MC phase volume sampling is shown to produce results consistent with those obtained using Gibbs Ensemble Monte Carlo (GEMC) simulations for the same intermolecular potential model.