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Beyond the mean-field approximation for pair correlations in classical density functional theory: Reference inhomogeneous non-associating monomeric fluids for use with SAFT-VR Mie DFT
被引:0
作者:
Bernet, Thomas
[1
,2
]
Ravipati, Srikanth
[1
,3
]
Cardenas, Harry
[1
]
Muller, Erich A.
[1
]
Jackson, George
[1
]
机构:
[1] Imperial Coll London, Dept Chem Engn, South Kensington Campus, London SW7 2AZ, England
[2] Univ Pau & Pays Adour, CNRS, Total, LFCR,E2S UPPA, Anglet, France
[3] ScaleSpace, SPARTA Biodiscovery, London W12 7RZ, England
基金:
英国工程与自然科学研究理事会;
关键词:
EQUATION-OF-STATE;
DIRECTIONAL ATTRACTIVE FORCES;
HARD-SPHERE FLUID;
PERTURBATION-THEORY;
ASSOCIATING FLUIDS;
CHAIN MOLECULES;
PHASE-EQUILIBRIA;
MODEL;
ADSORPTION;
INTERFACE;
D O I:
10.1063/5.0219968
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
A free-energy functional is presented to explicitly take into account pair correlations between molecules in inhomogeneous fluids. The framework of classical density functional theory (DFT) is used to describe the variation in the density of molecules interacting through a Mie (generalized Lennard-Jones) potential. Grand Canonical Monte Carlo simulations are performed for the systems to validate the new functional. The statistical associating fluid theory developed for Mie fluids (SAFT-VR Mie) is selected as a reference for the homogeneous bulk limit of the DFT and is applied here to systems of spherical non-associating particles. The importance of a correct description of the pair correlations for a reliable representation of the free energy in the development of the equation of state is duly noted. Following the Barker-Henderson high-temperature expansion, an analogous formulation is proposed from the general DFT formalism to develop an inhomogeneous equivalent of the SAFT-VR Mie free energy as a functional of the one-body density. In order to make use of this new functional in adsorption studies, a non-local version of the DFT is considered, with specific weighted densities describing the effects of neighboring molecules. The computation of these quantities is possible in three-dimensional space for any pore geometry with repulsive or attractive walls. We showcase examples to validate the new functional, revealing a very good agreement with molecular simulation. The new SAFT-DFT approach is well-adapted to describe realistic complex fluids.
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页数:27
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