(70j) Quantitatively Reliable Molecular Modeling and Simulation of Vapor-Liquid Equilibria

For a variety of low-molecular fluids, two-center Lennard-Jones plus point dipole (2CLJD) and two-center Lennard-Jones plus point quadrupole (2CLJQ) models, which describe bulk properties of pure-component vapor-liquid equilibria with a good accuracy, are available from the literature [1]. In the present work, these models are applied for simulating the vapor-liquid surface tension. Thereby, the literature models, which were adjusted to bulk properties, but not to interfacial properties, are validated against the surface tension of the real fluids.

By molecular dynamics simulation, employing a recently developed efficient long-range correction scheme [2, 3], it is found that on average, the literature models overestimate the vapor-liquid surface tension by 15 to 20% [3, 4]. To improve the overall accuracy of the models, optimization criteria based on the vapor pressure and the saturated liquid density, i.e., bulk properties which were previously taken into account during model parameterization, are combined with the vapor-liquid surface tension, which was not considered when the literature models were developed. This multicriteria optimization problem is addressed by constructing the Pareto front, i.e., the set of rational compromises between the competing objectives, from which models tailored to special needs can subsequently be chosen [5].

[1] J. Vrabec, J. Stoll, H. Hasse, J. Phys. Chem. B 105(48), 12126-12133, 2001.
[2] S. Werth, G. Rutkai, J. Vrabec, M. Horsch, H. Hasse, Mol. Phys. 112(17), 2227-2234, 2014.
[3] S. Werth, M. Horsch, H. Hasse, Mol. Phys. 113(23), 3750-3756, 2015.
[4] S. Werth, M. Horsch, H. Hasse, J. Chem. Phys. 144, 054702, 2016.
[5] K. Stöbener, P. Klein, M. Horsch, K. Küfer, H. Hasse, Fluid Phase Equilib. 411, 33-42, 2016.