First principles calculation of the elasticity of ice VIII and X

Jun Tsuchiya; Taku Tsuchiya

doi:10.1063/1.4973339

First principles calculation of the elasticity of ice VIII and X

J Chem Phys. 2017 Jan 7;146(1):014501. doi: 10.1063/1.4973339.

Authors

Jun Tsuchiya¹, Taku Tsuchiya¹

Affiliation

¹ Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577, Japan.

PMID: 28063424
DOI: 10.1063/1.4973339

Abstract

The elastic constants of ice VIII and ice X phases under pressure have been determined at static 0 K conditions using first principles calculation. A step-like increase of the elastic constants of ice VIII phase occurred at 100-110 GPa due to hydrogen bond symmetrization. The elastic constants, and the pressure dependencies of these constants, of ice X and VIII are completely distinct. Due to these differences, these two phases can be distinguished on the basis of the elastic behavior. Conversely, the experimental elastic constant of C₁₁ of ice VII gradually changes from an ice VIII like asymmetric hydrogen bond to a symmetric bond character within a wide pressure range. This finding suggests that the transition from ice VII to ice X starts around 30 GPa and completes at 110 GPa.