Total and excess properties of nonideal ternary fluid mixtures via isothermal-isobaric molecular dynamics simulation: size and energy parameter effects

We report isothermal-isobaric molecular dynamics simulation results for total and excess properties of 162 ternary mixtures of Lennard-Jones fluids. Simulations were performed at energy and size parameter ratios in the range (1 ≤ ϵCCϵAA ≤ 2; 1 ≤ σCCσAA ≤ 2). In these mixtures, the component A consists of the smallest atoms, while the component C consists of the biggest atoms. The energy and size parameter ratios of the component B lie in the range (1 ≤ ϵBBϵAA ≤ 1.75; 1 ≤ σBBσAA ≤ 1.75). Results are reported for mixture density, residual internal energy, excess enthalpy and excess volume of 120 equimolar mixtures and 42 nonequimolar mixtures at 5 different thermodynamic conditions: (kTϵAA = 1, PσAA3ϵAA = 0.5); (kTϵAA = 1.5, PσAA3ϵAA = 1.5); (kTϵAA = 2, PσAA3ϵAA = 1.2); (kTϵAA = 2, PσAA3ϵAA = 2.5) and (kTϵAA = 3, PσAA3ϵAA = 2.5). Some of these simulation results are used to test the accuracy of the recently developed statistical mechanical perturbation theory and van der Waals one-fluid theory of ternary mixtures. Perturbation theory is very successful in describing simulation results of highly nonideal mixtures, while van der Waals one-fluid theory can describe moderately nonideal mixtures only.