Anharmonic nuclear motion and the relative stability of hexagonal and cubic ice
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Publication Date
2015-06-08Journal Title
Physical Review X
ISSN
2160-3308
Publisher
APS
Volume
5
Number
021033
Language
English
Type
Article
Metadata
Show full item recordCitation
Engel, E., Monserrat Sanchez, B., & Needs, R. (2015). Anharmonic nuclear motion and the relative stability of hexagonal and cubic ice. Physical Review X, 5 (021033)https://doi.org/10.1103/PhysRevX.5.021033
Abstract
We use extensive first-principles quantum mechanical calculations to show that, although the static lattice and harmonic vibrational energies are almost identical, the anharmonic vibrational energy of hexagonal ice is significantly lower than that of cubic ice. This difference in anharmonicity is crucial, stabilising hexagonal ice compared with cubic ice by at least 1.4 meV/H2O, in agreement with experimental estimates. The difference in anharmonicity arises predominantly from molecular O-H bond stretching vibrational modes and is related to the different stacking of atomic layers.
Sponsorship
We acknowledge financial support from the Engineering and Physical Sciences Research Council of the UK [EP/J017639/1]. B. M. also acknowledges Robinson College, Cambridge, and the Cambridge Philosophical Society for a Henslow Research Fellowship. The calculations were performed on the Cambridge High Performance Computing Service facility and the HECToR and Archer facilities of the UK’s national high-performance computing service (for which access was obtained via the UKCP consortium [EP/K013564/1]).
Funder references
EPSRC (EP/J017639/1)
EPSRC (EP/K014560/1)
EPSRC (EP/F032773/1)
EPSRC (1208472)
Identifiers
External DOI: https://doi.org/10.1103/PhysRevX.5.021033
This record's URL: https://www.repository.cam.ac.uk/handle/1810/248333
Rights
Attribution 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by/2.0/uk/