First principles molecular dynamics study of filled ice hydrogen hydrate
We investigated structural changes, phase diagram, and vibrational properties of hydrogen hydrate in filled-ice phase C2 by using first principles molecular dynamics simulation. It was found that the experimentally reported “cubic” structure is unstable at low temperature and/or high pressure: The “...
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craippubl:10.1063/1.4746776 2024-02-11T10:05:49+01:00 First principles molecular dynamics study of filled ice hydrogen hydrate Zhang, Jingyun Kuo, Jer-Lai Iitaka, Toshiaki National Science Council Taiwan 2012 http://dx.doi.org/10.1063/1.4746776 https://pubs.aip.org/aip/jcp/article-pdf/doi/10.1063/1.4746776/13989271/084505_1_online.pdf en eng AIP Publishing The Journal of Chemical Physics volume 137, issue 8 ISSN 0021-9606 1089-7690 Physical and Theoretical Chemistry General Physics and Astronomy journal-article 2012 craippubl https://doi.org/10.1063/1.4746776 2024-01-26T09:48:15Z We investigated structural changes, phase diagram, and vibrational properties of hydrogen hydrate in filled-ice phase C2 by using first principles molecular dynamics simulation. It was found that the experimentally reported “cubic” structure is unstable at low temperature and/or high pressure: The “cubic” structure reflects the symmetry at high (room) temperature where the hydrogen bond network is disordered and the hydrogen molecules are orientationally disordered due to thermal rotation. In this sense, the “cubic” symmetry would definitely be lowered at low temperature where the hydrogen bond network and the hydrogen molecules are expected to be ordered. At room temperature and below 30 GPa, it is the thermal effects that play an essential role in stabilizing the structure in “cubic” symmetry. Above 60 GPa, the hydrogen bonds in the framework would be symmetrized and the hydrogen bond order-disorder transition would disappear. These results also suggest the phase behavior of other filled-ice hydrates. In the case of rare gas hydrate, there would be no guest molecules’ rotation-nonrotation transition since the guest molecules keep their spherical symmetry at any temperature. On the contrary methane hydrate MH-III would show complex transitions due to the lower symmetry of the guest molecule. These results would encourage further experimental studies, especially nuclear magnetic resonance spectroscopy and neutron scattering, on the phases of filled-ice hydrates at high pressures and/or low temperatures. Article in Journal/Newspaper Methane hydrate AIP Publishing The Journal of Chemical Physics 137 8 |
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AIP Publishing |
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English |
topic |
Physical and Theoretical Chemistry General Physics and Astronomy |
spellingShingle |
Physical and Theoretical Chemistry General Physics and Astronomy Zhang, Jingyun Kuo, Jer-Lai Iitaka, Toshiaki First principles molecular dynamics study of filled ice hydrogen hydrate |
topic_facet |
Physical and Theoretical Chemistry General Physics and Astronomy |
description |
We investigated structural changes, phase diagram, and vibrational properties of hydrogen hydrate in filled-ice phase C2 by using first principles molecular dynamics simulation. It was found that the experimentally reported “cubic” structure is unstable at low temperature and/or high pressure: The “cubic” structure reflects the symmetry at high (room) temperature where the hydrogen bond network is disordered and the hydrogen molecules are orientationally disordered due to thermal rotation. In this sense, the “cubic” symmetry would definitely be lowered at low temperature where the hydrogen bond network and the hydrogen molecules are expected to be ordered. At room temperature and below 30 GPa, it is the thermal effects that play an essential role in stabilizing the structure in “cubic” symmetry. Above 60 GPa, the hydrogen bonds in the framework would be symmetrized and the hydrogen bond order-disorder transition would disappear. These results also suggest the phase behavior of other filled-ice hydrates. In the case of rare gas hydrate, there would be no guest molecules’ rotation-nonrotation transition since the guest molecules keep their spherical symmetry at any temperature. On the contrary methane hydrate MH-III would show complex transitions due to the lower symmetry of the guest molecule. These results would encourage further experimental studies, especially nuclear magnetic resonance spectroscopy and neutron scattering, on the phases of filled-ice hydrates at high pressures and/or low temperatures. |
author2 |
National Science Council Taiwan |
format |
Article in Journal/Newspaper |
author |
Zhang, Jingyun Kuo, Jer-Lai Iitaka, Toshiaki |
author_facet |
Zhang, Jingyun Kuo, Jer-Lai Iitaka, Toshiaki |
author_sort |
Zhang, Jingyun |
title |
First principles molecular dynamics study of filled ice hydrogen hydrate |
title_short |
First principles molecular dynamics study of filled ice hydrogen hydrate |
title_full |
First principles molecular dynamics study of filled ice hydrogen hydrate |
title_fullStr |
First principles molecular dynamics study of filled ice hydrogen hydrate |
title_full_unstemmed |
First principles molecular dynamics study of filled ice hydrogen hydrate |
title_sort |
first principles molecular dynamics study of filled ice hydrogen hydrate |
publisher |
AIP Publishing |
publishDate |
2012 |
url |
http://dx.doi.org/10.1063/1.4746776 https://pubs.aip.org/aip/jcp/article-pdf/doi/10.1063/1.4746776/13989271/084505_1_online.pdf |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
The Journal of Chemical Physics volume 137, issue 8 ISSN 0021-9606 1089-7690 |
op_doi |
https://doi.org/10.1063/1.4746776 |
container_title |
The Journal of Chemical Physics |
container_volume |
137 |
container_issue |
8 |
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1790603015043940352 |