The feasibility of using all-atom

first-principle force fields to predict thermodynamic properties was discussed.A newly developed TEAM force field was used to calculate fluid densities

vaporization enthalpies

heats of mixing

Henry’s law constants

and vapor pressures for representative molecules in various thermodynamic states.The force field was validated by using the thermodynamic data of gas and liquid phases

and then used to make predictions without any empirical adjustment.Initial results indicated that predictions of liquid densities and vaporization enthalpies were successful.The results comparable with experimental measurements could be obtained at extended state points.The prediction of heats of mixing required very high accuracy in evaluating cohesive energies for pure fluids

and the calculation of Henry’s law constants was extreme sensitive to fluid densities.Both required high quality of the force fields parameters.In order to calculate the vapor pressures and liquid-vapor coexistence densities effectively with the all-atom force fields

a new iterative procedure based on integration of the Clausius-Clapeyron equation was proposed.