We propose three phases of H 2O under ultrahigh pressure. Our structural search was performed using an adaptive genetic algorithm which allows an extensive exploration of crystal structure at density functional theory accuracy. The sequence of pressure-induced transitions beyond ice X at 0 K should be ice X→Pbcm→Pbca→Pmc2 1→P2 1→P2 1/c phases. Across the Pmc2 1-P2 1 transition, the coordination number of oxygen increases from 4 to 5 with a significant increase of density. All stable crystalline phases have nonmetallic band structures up to 7 TPa.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Dec 13 2011|