Vibrational modes of methane in the structure H clathrate hydrate from ab initio molecular dynamics simulation

Masaki Hiratsuka, Ryo Ohmura, Amadeu K. Sum, Kenji Yasuoka

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Vibrational spectra of guest molecules in clathrate hydrates are frequently measured to determine the characteristic signatures of the molecular environment and dynamical properties of guest-host interactions. Here, we present results of our study on the vibrational frequencies of methane molecules in structure H clathrate hydrates, namely, in the 5 12 and 4 35 66 3 cages, as the frequencies of stretching vibrational modes in these environments are still unclear. The vibrational spectra of methane molecules in structure H clathrate hydrate were obtained from ab initio molecular dynamics simulation and computed from Fourier transform of autocorrelation functions for each distinct vibrational mode. The calculated symmetric and asymmetric stretching vibrational frequencies of methane molecules were found to be lower in the 4 35 66 3 cages than in the 5 12 cages (3.8 cm -1 for symmetric stretching and 6.0 cm -1 for asymmetric stretching). The C-H bond length and average distance between methane molecules and host-water molecules in 4 35 66 3 cages were slightly longer than those in the 5 12 cages.

Original languageEnglish
Article number144306
JournalJournal of Chemical Physics
Volume137
Issue number14
DOIs
Publication statusPublished - 2012 Oct 14

ASJC Scopus subject areas

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

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