Comparison of forcefields for molecular dynamics simulations of hydrocarbon phase diagrams

VV Pisarev and SA Zakharov, XXXII INTERNATIONAL CONFERENCE ON INTERACTION OF INTENSE ENERGY FLUXES WITH MATTER (ELBRUS 2017), 946, 012100 (2018).

DOI: 10.1088/1742-6596/946/1/012100

Molecular dynamics calculations of vapor-liquid equilibrium of methane- n-butane mixture are performed. Three force-field models are tested: the TraPPE-UA united-atom forcefield, LOPLS-AA all-atom forcefield and a fully flexible version of the TraPPE-EH all-atom forcefield. All those forcefields reproduce well the composition of liquid phase in the mixture as a function of pressure at the 300 K isotherm, while significant discrepancies from experimental data are observed in the saturated vapor compositions with OPLS-AA and TraPPE-UA forcefields. The best agreement with the experimental phase diagram is found with TraPPE- EH forcefield which accurately reproduces compositions of both liquid and vapor phase. This forcefield can be recommended for simulation of two-phase hydrocarbon systems.

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