A Set of Molecular Models for Symmetric Quadrupolar Fluids

Abstract

propylene. The models are based on the two-center Lennard-Jones plus pointquadrupole pair potential (2CLJQ). The model parameters were adjusted to experimental vapor-liquid equilibria of the pure fluids using a highly efficient procedure. The application of these models to the calculation of vaporliquid equilibria and homogeneous fluid state points by molecular simulation shows good agreement with experimental results. Numbers for model parameters correlate reasonably with geometric data of the molecules and experimental quadrupole moments. Due to the compatibility of the presented models, applications to the prediction of vapor-liquid equilibria of mixtures are straightforward.

Molecular simulation of the thermophysical properties and phase behaviour of impure CO2 relevant to CCS

“…For CO 2 this is close to the working temperature of CCS transport pipelines. Indeed, simulation results from this force-field are within ∼ 2% of experiments on pure CO 2 for the density and vapour pressure in the CCS transport window 22 . However, the temperature ranges used to fit the impurity force-fields for N 2 and O 2 are less well matched to the CCS transport problem.…”

“…To compound this we also require that they predict properties of a mixture of which the impurity is only a small percentage. This is in contrast to the original fitting, which only used self interactions to optimise for the pure material properties 22 . There are some CO 2 binary mixtures that have been simulated with the available force-fields and good agreement with VLE data was obtained with the optimisation of the Lorenz-Bertholet mixing parameters 23 .…”

“…Similarly, a CO 2 force-field has been obtained using a three-centre Lennard-Jones plus point quadrupole model, to represent this triatomic molecule 27 (see figure 1b and table 1). As Ar is monatomic and non-polar, we use a single Lennard-Jones site with no quadrupole 22 . These literature force-fields were obtained by fitting self interactions to experimental data for the corresponding pure fluid around its critical point.…”

Response to “Comment on ‘The gas-liquid surface tension of argon: A reconciliation between experiment and simulation”’ [J. Chem. Phys. 142, 107101 (2015)]

“…In our paper, we only use a LJ potential with parameters developed by Vrabec et al 3 as a model to test the proposition that a cutoff distance of r c = 18 Å without a z-dependent long range correction to the potential energy allows for an accurate calculation of the surface tension. We clearly show that this is the case in the paper.…”

Communication: Fundamental equation of state correlation with hybrid data sets

“…The typical accuracy of reproduction is ±5% for vapor pressure and ±1% for saturated liquid density. [9][10][11][12][13][14][15][16] However, it is usually not known how molecular interaction models perform in homogeneous regions. We performed simulations for some ten molecular models [9][10][11][12][13][14][15][16] representing fluids of very different nature at various state points in the homogeneous regions, and compared A r mn results with the best available FEOS correlations from the literature.…”