New high-pressure phases of ice.

  title={New high-pressure phases of ice.},
  author={Demontis and LeSar and Klein},
  journal={Physical review letters},
  volume={60 22},
An ionic model has been used in conjunction with classical constant-pressure molecular-dynamics calculations to explore the properties of possible high-pressure phases of ice. Around 100 GPa, the model is found to convert from the symmetric hydrogen-bonded cuprite structure (ice X) to a fully ordered antifluorite structure. On heating, the new phase, ice XI, becomes a fast-ion proton conductor. 
Temperature and pressure-induced phase transitions in ice
Abstract In the liquid state, water molecules tend to be surrounded tetrahedrally by four other molecules. This tendency gives rise to a three-dimensional open network which is a feature of most of
Ab-initio simulation of phase transformations under pressure
We have recently devised a new method for ab initio simulation of solid-solid phase transformation under pressure. The method is here applied to the study of ice at Mbar pressure, the solid-state
New phases of hydrogen-bonded systems at extreme conditions
We study the behaviour of hydrogen-bonded systems under high pressure and temperature. First principle calculations of formic acid under isotropic pressure up to 70 GPa reveal the existence of a
Superionic and metallic states of water and ammonia at giant planet conditions.
The phase diagrams of water and ammonia were determined by constant pressure ab initio molecular dynamic simulations at pressures (30 to 300 gigapascal) and temperatures (300 to 7000 kelvin) of relevance for the middle ice layers of the giant planets Neptune and Uranus to improve the understanding of the properties of the middle icy layers.
Melting of ice under pressure
The onset of significant proton diffusion in ice-VII as a function of increasing temperature is found to be gradual and bears many similarities to that of a type-II superionic solid.
Equation of state and metallization of ice under very high pressure
The equation of state and the electronic bandstructure of ice have been calculated in the recently proposed high-pressure phase XI (anti-fluorite structure) by using the local-density approximation
Equation of state of H2O under ultra-high pressure
The equation of state (EOS) and metallization of ice in a recently proposed ultra-high-pressure phase (anti-fluorite structure) have been studied from first principles by using the local-density
High pressure partially ionic phase of water ice.
The pressure-induced formation of a partially ionic phase (monoclinic P2(1) structure) consisting of coupled alternate layers of (OH)(δ-) and (H(3)O)( δ+) (δ=0.62) in water ice predicted by particle-swarm optimization structural search at zero temperature and pressures of >14 Mbar is shown.
Hot black ices
At high pressure and temperature, water forms two crystalline phases, known as hot ‘black’ ices due to their partial opaqueness. A detailed characterization of these phases may explain magnetic field