### Abstract

Original language | English |
---|---|

Pages (from-to) | 026712.1-026712.14 |

Number of pages | 14 |

Journal | Physical Review E |

Volume | 77 |

Issue number | 2 |

DOIs | |

Publication status | Published - 28 Feb 2008 |

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### Keywords

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

### Cite this

*Physical Review E*,

*77*(2), 026712.1-026712.14. https://doi.org/10.1103/PhysRevE.77.026712

}

*Physical Review E*, vol. 77, no. 2, pp. 026712.1-026712.14. https://doi.org/10.1103/PhysRevE.77.026712

**Survey of classical density functionals for modelling hydrogen physisorption at 77 K.** / Sweatman, M.B.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Survey of classical density functionals for modelling hydrogen physisorption at 77 K

AU - Sweatman, M.B.

PY - 2008/2/28

Y1 - 2008/2/28

N2 - 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.

AB - 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.

KW - adsorption

KW - density functional theory

KW - graphite

KW - harmonic oscillators

KW - hydrogen

KW - polymers

KW - chemical engineering

U2 - 10.1103/PhysRevE.77.026712

DO - 10.1103/PhysRevE.77.026712

M3 - Article

VL - 77

SP - 026712.1-026712.14

JO - Physical Review E

JF - Physical Review E

SN - 1539-3755

IS - 2

ER -