An extensional TraPPE-UA force field for N

N-dimethyl-formamide(DMF) was developed by combination of the quantum chemistry calculation and Gibbs ensemble Monte Carlo simulation

which lays the foundation for the simulation of vapor-liquid phase equilibrium with DMF. First of all

the vapor-liquid phase equilibrium for DMF was calculated in the NVT-Gibbs ensemble by using this new force filed. The results show that the new force field can be used to accurately calculate the saturated liquid densities

vapor pressures

normal boiling point

critical point and heats of vaporization of DMF. Secondly

the vapor-liquid equilibrium for binary mixtures of acetonitrile-methanol

DMF-methanol

DMF-acetonitrile were computed in the NPT-Gibbs ensemble by adopting the TraPPE-UA force field. These simulation results were in good agreement with the experimental data

which validated the reliability of this model. Finally

the vapor-liquid equilibrium data of ternary mixture of acetonitrile-methanol-DMF were predicted in the NPT-Gibbs ensemble

which can provide basic data for design and optimization of the separation process of acetonitrile and methanol.