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Relationship between local molecular field theory and density functional theory for non-uniform liquids

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journal contribution
posted on 31.01.2013, 09:08 by Andrew ArcherAndrew Archer, Robert Evans
The local molecular field theory (LMF) developed by Weeks and co-workers has proved successful for treating the structure and thermodynamics of a variety of non-uniform liquids. By reformulating LMF in terms of one-body direct correlation functions we recast the theory in the framework of classical density functional theory (DFT). We show that the general LMF equation for the effective reference potential φR(r) follows directly from the standard mean-field DFT treatment of attractive interatomic forces. Using an accurate (fundamental measures) DFT for the non-uniform hard-sphere reference fluid we determine φR(r) for a hard-core Yukawa liquid adsorbed at a planar hard wall. In the approach to bulk liquid-gas coexistence we find the effective potentials exhibit rich structure that can include damped oscillations at large distances from the wall as well as the repulsive hump near the wall required to generate the low density “gas” layer characteristic of complete drying. We argue that it would be difficult to obtain the same level of detail from other (non-DFT based) implementations of LMF. LMF emphasizes the importance of making an intelligent division of the interatomic pair potential of the full system into a reference part and a remainder that can be treated in mean-field approximation.We investigate different divisions for an exactly solvable one-dimensional model where the pair potential has a hard-core plus a linear attractive tail. Results for the structure factor and the equation of state of the uniform fluid show that including a significant portion of the attraction in the reference system can be much more accurate than treating the full attractive tail in mean-field approximation. We discuss further aspects of the relationship between LMF and DFT.

History

School

  • Science

Department

  • Mathematical Sciences

Citation

ARCHER, A.J. and EVANS, R., 2013. Relationship between local molecular field theory and density functional theory for non-uniform liquids. Journal of Chemical Physics, 138, 014502; http://dx.doi.org/10.1063/1.4771976 (14 pages)

Publisher

© American Institute of Physics

Version

AM (Accepted Manuscript)

Publication date

2013

Notes

This article was published in the Journal of Chemical Physics [© American Institute of Physics] and the definitive version is available at: http://dx.doi.org/10.1063/1.4771976

ISSN

0021-9606

eISSN

1089-7690

Language

en

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