title: Encapsulation kinetics and dynamics of carbon monoxide in clathrate hydrate.
abstract: Carbon monoxide clathrate hydrate is a potentially important constituent in the solar system. In contrast to the well-established relation between the size of gaseous molecule and hydrate structure, previous work showed that carbon monoxide molecules preferentially form structure-I rather than structure-II gas hydrate. Resolving this discrepancy is fundamentally important to understanding clathrate formation, structure stabilization and the role the dipole moment/molecular polarizability plays in these processes. Here we report the synthesis of structure-II carbon monoxide hydrate under moderate high-pressure/low-temperature conditions. We demonstrate that the relative stability between structure-I and structure-II hydrates is primarily determined by kinetically controlled cage filling and associated binding energies. Within hexakaidecahedral cage, molecular dynamic simulations of density distributions reveal eight low-energy wells forming a cubic geometry in favour of the occupancy of carbon monoxide molecules, suggesting that the carbon monoxide-water and carbon monoxide-carbon monoxide interactions with adjacent cages provide a significant source of stability for the structure-II clathrate framework.
authors.affiliation: 1] LANSCE, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA [2] National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [3] HiPSEC, Department of Physics and Astronomy, University of Nevada, Las Vegas, Nevada 89154, USA.
authors.forename: Jinlong
authors.initials: J
authors.lastname: Zhu
authors.affiliation: 1] T-Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA [2] Division of Functional Materials and Nanodevices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China.
authors.forename: Shiyu
authors.initials: S
authors.lastname: Du
authors.affiliation: 1] LANSCE, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA [2] National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Yu
authors.affiliation: LANSCE, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Zhang
authors.affiliation: EES Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Hongwu
authors.initials: H
authors.lastname: Xu
authors.affiliation: LANSCE, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Sven C
authors.initials: SC
authors.lastname: Vogel
authors.affiliation: T-Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Germann
authors.affiliation: Departments of Chemistry and Earth and Atmospheric Science, Purdue University, West Lafayette, Indiana 47906, USA.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Francisco
authors.affiliation: National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Fujio
authors.initials: F
authors.lastname: Izumi
authors.affiliation: 1] National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan [2].
authors.forename: Koichi
authors.initials: K
authors.lastname: Momma
authors.affiliation: 1] National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan [2].
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Kawamura
authors.affiliation: National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Changqing
authors.initials: C
authors.lastname: Jin
authors.affiliation: 1] LANSCE, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA [2] National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [3] HiPSEC, Department of Physics and Astronomy, University of Nevada, Las Vegas, Nevada 89154, USA.
authors.forename: Yusheng
authors.initials: Y
authors.lastname: Zhao