Molecular simulation of the surface tension of real fluids

TL;DR

This study validates molecular models of 38 real fluids by comparing molecular dynamics simulation results of surface tension with experimental data, finding models generally overestimate but are within 20% accuracy.

Contribution

It provides a comprehensive validation of complex molecular models against experimental surface tension data without model adjustment for interfacial properties.

Findings

Models overestimate surface tension but within 20% deviation.

Validation covers 38 real fluids with complex interaction sites.

Previous studies' results are corroborated with similar overestimation levels.

Abstract

Molecular models of real fluids are validated by comparing the vapor-liquid surface tension from molecular dynamics (MD) simulation to correlations of experimental data. The considered molecular models consist of up to 28 interaction sites, including Lennard-Jones sites, point charges, dipoles and quadrupoles. They represent 38 real fluids, such as ethylene oxide, sulfur dioxide, phosgene, benzene, ammonia, formaldehyde, methanol and water, and were adjusted to reproduce the saturated liquid density, vapor pressure and enthalpy of vaporization. The models were not adjusted to interfacial properties, however, so that the present MD simulations are a test of model predictions. It is found that all of the considered models overestimate the surface tension. In most cases, however, the relative deviation between the simulation results and correlations to experimental data is smaller than 20 %. This observation corroborates the outcome of our previous studies on the surface tension of 2CLJQ and 2CLJD fluids where an overestimation of the order of 10 to 20 % was found.