%0 Journal Article
%A Prager, M.
%A Press, W.
%T Methane clathrate: CH4 quantum rotor state dependent rattling potential
%J The journal of chemical physics
%V 125
%@ 0021-9606
%C Melville, NY
%I American Institute of Physics
%M PreJuSER-57070
%P 214703
%D 2006
%Z Record converted from VDB: 12.11.2012
%X In methane hydrate the dominant peak in the density of states above 3 meV represents a rattling mode of the guest molecule CH(4) in the large ice cages. This mode shifts from 6.7 meV at T=4.5 K to T=30 K to 7.14 meV with conversion of CH(4) guest molecules into the tunneling ground state. The less symmetric angular density distribution PsiPsi(*) in the excited rotational state compared to the ground state allows the methane to fit better in the orientation dependent cage potential surface. This leads to a larger average distance to the cage-forming molecules with a weaker potential and a reduced rattling energy. A two state single particle model with characteristic rattling energies of 5.20 meV for pure T-methane and 7.3 meV for pure A-methane weighted by the population factors can fit the data.
%K J (WoSType)
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:17166036
%U <Go to ISI:>//WOS:000242646200029
%R 10.1063/1.2400031
%U https://juser.fz-juelich.de/record/57070