Structure, dynamics and thermodynamic stability of high-pressure ices and clathrate hydrates

Abstract

We present the recent development of simulation studies on structure and dynamics of high-pressure ices and filled ices. After surveying the representative structures of ices, focus is placed on some properties of one of the ice polymorphs, plastic ice, which has been theoretically predicted but not yet been found experimentally. Its intervention between ice VII and liquid water enables to account for large discrepancies among various experimental melting curves of ice VII. We also examine the dynamical properties of the filled ice in which hydrogen molecules are contained in void space of the low-pressure cubic ice. In contrast to the plastic ice, which has a bearing on ice VII, it exhibits a gradual change to each rotator phase of guest hydrogen and/or host water molecules.

Keywords::

• ice
• filled ice
• thermodynamic stability
• structure
• dynamics

Acknowledgement

The calculations were performed at the Institute for Molecular Science.

Additional information

Funding

This work was supported by Grant-in-Aid by the JSPS and by the Computational Materials Science Initiative (CMSI), MEXT, Japan.