Anharmonic nuclear motion and the relative stability of hexagonal and cubic ice
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Authors
Engel, EA
Monserrat, B
Needs, RJ
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.
Description
Keywords
cond-mat.mtrl-sci, cond-mat.mtrl-sci
Journal Title
Physical Review X
Conference Name
Journal ISSN
2160-3308
2160-3308
2160-3308
Volume Title
5
Publisher
American Physical Society (APS)
Publisher DOI
Sponsorship
Engineering and Physical Sciences Research Council (EP/J017639/1)
Engineering and Physical Sciences Research Council (EP/K014560/1)
Engineering and Physical Sciences Research Council (EP/F032773/1)
EPSRC (1208472)
Engineering and Physical Sciences Research Council (EP/K014560/1)
Engineering and Physical Sciences Research Council (EP/F032773/1)
EPSRC (1208472)
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]).