Structure of liquid water under high pressure up to 17 GPa

Katayama, Yoshinori; Hattori, Takanori   ; Saito, Hiroyuki; Ikeda, Takashi; Aoki, Katsutoshi; Fukui, Hiroshi*; Funakoshi, Kenichi*

The structure of liquid water was studied along the melting curve up to 17.1 GPa and 850 K by in situ X-ray diffraction. At low pressures, the local structure changed toward a simple liquid-like structure through an increase in the coordination number of water molecules. Once densely packed structure of water molecules was achieved around 4 GPa, the volume was reduced through the decrease of the intermolecular distance on further compression. Classical molecular dynamics simulations well reproduced the experimental results although the degree of agreement depended on pressure. Limitations of the pair potential model were discussed.