title: Unusual crystalline and polycrystalline structures in methane hydrates.
abstract: We present previously unreported crystalline and polycrystalline structures for methane hydrates obtained at relatively low pressures. These structures, which contain unusual cages with 12 pentagonal faces and 3 hexagonal faces, were observed during the atomistic simulations of the crystal growth of sI and sII methane hydrates. These 51263 cages have a significant impact on the structure of the resulting crystal and could explain several experimental observations regarding in-situ transformations between sI and sII hydrates. We document a previously unidentified structure of methane hydrates which we designate structure sK. Additionally, we predict a polycrystalline structure consisting of this new hydrate and sI and suggest a mechanism for the formation of a polycrystalline structure consisting of sequences of sI and sII hydrates.
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4.
authors.forename: Jenel
authors.initials: J
authors.lastname: Vatamanu
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kusalik