Structural Evolution of Compressing Amorphous Ice

Molecular dynamics simulation is employed to study structural evolutionduring compressing low density amorphous ice from one atmosphere to2.5GPa. The calculated results show that high density amorphous ice isformed under intermediate pressure of about 1.0GPa and O--O--O angleranges from about 83° to 113° and O--H...O is bent from 112° to 160°. The very high density amorphous ice is also formed under the pressure larger than 1.4GPa and interstitial molecules are found in 0.3--0.4 just beyond the nearest O--O distance. Low angle O--H...O disappears and it is believed thatthese hydrogen bonds are broken or re-bonded under high pressures.