Ground-state structures of ice at high pressures from ab initio random structure searching
Abstract
Ab initio random structure searching based on density functional theory is used to determine the ground-state structures of ice at high pressures. Including estimates of lattice zero-point energies, ice is predicted to adopt at least three crystal phases beyond Pbcm. The underlying sublattice of O atoms remains similar among them, and the transitions can be characterized by reorganizations of the hydrogen bonds. The symmetric hydrogen bonds of ice X and Pbcm are initially lost as ice transforms to structures with symmetries Pmc21 (800-950 GPa) and P21 (1.17 TPa), but they are eventually regained at 5.62 TPa in a layered structure C2/m. The P21→C2/m transformation also marks the insulator-to-metal transition in ice, which occurs at a significantly higher pressure than recently predicted.
- Publication:
-
Physical Review B
- Pub Date:
- December 2011
- DOI:
- 10.1103/PhysRevB.84.220104
- arXiv:
- arXiv:1106.1941
- Bibcode:
- 2011PhRvB..84v0104M
- Keywords:
-
- 64.70.K-;
- 62.50.-p;
- 71.30.+h;
- 96.15.Nd;
- Solid-solid transitions;
- High-pressure effects in solids and liquids;
- Metal-insulator transitions and other electronic transitions;
- Interiors;
- Condensed Matter - Other Condensed Matter;
- Astrophysics - Earth and Planetary Astrophysics;
- Condensed Matter - Materials Science;
- Physics - Computational Physics
- E-Print:
- 10 pages