Dynamical cage behaviour and hydrogen migration in hydrogen and hydrogen-tetrahydrofuran clathrate hydrates

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dc.contributor.author Gorman, Paul D.
dc.contributor.author English, Niall J.
dc.contributor.author MacElroy, J. M. Don
dc.date.accessioned 2012-06-07T15:10:15Z
dc.date.available 2012-06-07T15:10:15Z
dc.date.copyright 2012 American Institute of Physics en
dc.date.issued 2012-01-24
dc.identifier.citation Journal of Chemical Physics en
dc.identifier.issn 0021-9606 (print)
dc.identifier.uri http://hdl.handle.net/10197/3625
dc.description.abstract Classical equilibrium molecular dynamics(MD) simulations have been performed to investigate dynamical properties of cage radial breathing modes and intra- and inter-cage hydrogen migration in both pure hydrogen and mixed hydrogen-tetrahydrofuran sII hydrates at 0.05 kbar and up to 250K. For the mixed H2-THF system in which there is single H2 occupation of the small cage (labelled ‘1SC 1LC’), we find that no H2 migration occurs, and this is also the case for pure H2 hydrate with single small-cavity occupation and quadruple occupancy for large cages (dubbed ‘1SC 4LC’). However, for the more densely-filled H2-THF and pure- H2 systems, in which there is double H2 occupation in the small cage (dubbed ‘2SC 1LC’ and ‘2SC 4LC’, respectively), there is an onset of inter-cage H2 migration events from the small cages to neighbouring cavities at around 200 K, with an approximate Arrhenius temperature-dependence for the migration rate from 200 to 250 K. It was found that these ‘cage hopping’ events are facilitated by temporary openings of pentagonal small-cage faces with the relaxation and reformation of key stabilising hydrogen bonds during and following passage. The cages remain essentially intact up to 250 K, save for transient hydrogen bond weakening and reformation during and after inter-cage hydrogen diffusion events in the 200 to 250 K range. The ‘breathing modes’, or underlying frequencies governing the variation in the cavities’ radii, exhibit a certain overlap with THF rattling motion in the case of large cavities, while a there is some overlap of small cages’ radial breathing modes with lattice acoustic modes. en
dc.description.sponsorship Science Foundation Ireland en
dc.format.extent 454755 bytes
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher American Institute of Physics en
dc.relation.requires Chemical and Bioprocess Engineering Research Collection en
dc.subject Molecular dynamics en
dc.subject Hydrogen hydrate en
dc.subject THF hydrate en
dc.subject Breathing modes en
dc.subject Migration en
dc.subject.lcsh Molecular dynamics en
dc.subject.lcsh Hydrates en
dc.subject.lcsh Hydrogen en
dc.subject.lcsh Chemical bonds en
dc.title Dynamical cage behaviour and hydrogen migration in hydrogen and hydrogen-tetrahydrofuran clathrate hydrates en
dc.type Journal Article en
dc.internal.availability Full text available en
dc.status Peer reviewed en
dc.identifier.volume 136 en
dc.identifier.issue 4 en
dc.identifier.startpage 0044506 en
dc.identifier.doi 10.1063/1.3677188
dc.neeo.contributor Gorman|Paul D.|aut| en
dc.neeo.contributor English|Niall J.|aut| en
dc.neeo.contributor MacElroy|J. M. Don|aut| en
dc.description.admin ke, ab, is - TS 26.04.12 en


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