Survey of classical density functionals for modelling hydrogen physisorption at 77 K

M.B. Sweatman

Research output: Contribution to journalArticle

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Abstract

This work surveys techniques based on classical density functionals for modeling the quantum dispersion of physisorbed hydrogen at 77 K. Two such techniques are examined in detail. The first is based on the "open ring approximation" (ORA) of Broukhno et al., and it is compared with a technique based on the semiclassical approximation of Feynman and Hibbs (FH). For both techniques, a standard classical density functional is used to model hydrogen molecule-hydrogen molecule (i.e., excess) interactions. The three-dimensional (3D) quantum harmonic oscillator (QHO) system and a model of molecular hydrogen adsorption into a graphitic slit pore at 77 K are used as benchmarks. Density functional results are compared with path-integral Monte Carlo simulations and with exact solutions for the 3D QHO system. It is found that neither of the density functional treatments are entirely satisfactory. However, for hydrogen physisorption studies at 77 K the ORA based technique is generally superior to the FH based technique due to a fortunate cancellation of errors in the density functionals used. But, if more accurate excess functionals are used, the FH technique would be superior.
Original languageEnglish
Pages (from-to)026712.1-026712.14
Number of pages14
JournalPhysical Review E
Volume77
Issue number2
DOIs
Publication statusPublished - 28 Feb 2008

Fingerprint

functionals
Hydrogen
hydrogen
Modeling
Density Functional
harmonic oscillators
approximation
Harmonic Oscillator
Excess
rings
Molecules
cancellation
Ring
Semiclassical Approximation
slits
molecules
Approximation
Curvilinear integral
Cancellation
Adsorption

Keywords

  • adsorption
  • density functional theory
  • graphite
  • harmonic oscillators
  • hydrogen
  • polymers
  • chemical engineering

Cite this

Sweatman, M.B. / Survey of classical density functionals for modelling hydrogen physisorption at 77 K. In: Physical Review E. 2008 ; Vol. 77, No. 2. pp. 026712.1-026712.14.
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Survey of classical density functionals for modelling hydrogen physisorption at 77 K. / Sweatman, M.B.

In: Physical Review E, Vol. 77, No. 2, 28.02.2008, p. 026712.1-026712.14.

Research output: Contribution to journalArticle

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