Structure and dynamics of empty cages in xenon clathrate hydrate

Tomoko Ikeda-Fukazawa, Yohei Yamaguchi, Kazushige Nagashima, Katsuyuki Kawamura

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We performed molecular dynamics calculations of xenon clathrate hydrate to investigate the effects of empty cages on the structure and dynamics of the surrounding lattice. The distinct structure and dynamics of the empty cages, and cages including Xe, which coexist in the lattice, were analyzed. The results show that the ellipsoidal tetrakaidecahedral cage shrinks along the minor 〈 100 〉 axis and expands along the major 〈 100 〉 axis due to the absence of Xe from the cage, whereas the dodecahedral cage shrinks isotropically. These distortions of the empty cages cause a reduction in the lattice constant and an enhancement of the thermal vibrations of the surrounding lattice. The vibrational density of states shows that the hydrogen bonds consisting of the tetrakaidecahedral cage are strengthened by the absence of Xe, whereas those of the dodecahedral cage are weakened. These results show differing mechanisms of guest-host interaction for the two types of cages including Xe. Repulsion is the dominant guest-host interaction for the dodecahedral cage, as proposed by previous studies. For the tetrakaidecahedral cage, however, attractive interaction is dominant along the major 〈 100 〉 axis, whereas repulsive interaction is dominant along the minor 〈 100 〉 axis. The present results suggest that a small number of empty cages can affect not only the local structures but also the macroscopic properties of the crystal. It is concluded that the distortions of the empty cages are one of the important factors governing the density and phase equilibrium of clathrate hydrates.

Original languageEnglish
Article number224506
JournalThe Journal of Chemical Physics
Volume129
Issue number22
DOIs
Publication statusPublished - 2008
Externally publishedYes

Fingerprint

Xenon
clathrates
Hydrates
hydrates
xenon
Phase equilibria
Lattice constants
Molecular dynamics
Hydrogen bonds
interactions
Crystals
hydrogen bonds
molecular dynamics
vibration
augmentation
causes
crystals
Hot Temperature

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Ikeda-Fukazawa, T., Yamaguchi, Y., Nagashima, K., & Kawamura, K. (2008). Structure and dynamics of empty cages in xenon clathrate hydrate. The Journal of Chemical Physics, 129(22), [224506]. https://doi.org/10.1063/1.3033550

Structure and dynamics of empty cages in xenon clathrate hydrate. / Ikeda-Fukazawa, Tomoko; Yamaguchi, Yohei; Nagashima, Kazushige; Kawamura, Katsuyuki.

In: The Journal of Chemical Physics, Vol. 129, No. 22, 224506, 2008.

Research output: Contribution to journalArticle

Ikeda-Fukazawa, T, Yamaguchi, Y, Nagashima, K & Kawamura, K 2008, 'Structure and dynamics of empty cages in xenon clathrate hydrate', The Journal of Chemical Physics, vol. 129, no. 22, 224506. https://doi.org/10.1063/1.3033550
Ikeda-Fukazawa, Tomoko ; Yamaguchi, Yohei ; Nagashima, Kazushige ; Kawamura, Katsuyuki. / Structure and dynamics of empty cages in xenon clathrate hydrate. In: The Journal of Chemical Physics. 2008 ; Vol. 129, No. 22.
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