Anharmonic nuclear motion and the relative stability of hexagonal and cubic ice
Physical Review X
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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
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.
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]).
External DOI: https://doi.org/10.1103/PhysRevX.5.021033
This record's URL: https://www.repository.cam.ac.uk/handle/1810/248333
Attribution 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by/2.0/uk/