New ultrahigh pressure phases of H2O ice predicted using an adaptive genetic algorithm

TL;DR

This paper predicts three new ultrahigh pressure phases of H2O ice using an adaptive genetic algorithm, revealing complex phase transitions and structural changes up to 7 TPa.

Contribution

It introduces a novel computational approach to explore H2O ice phases, identifying new stable structures and transition sequences under extreme pressures.

Findings

Discovered three new high-pressure ice phases.

Identified a sequence of pressure-induced phase transitions.

All phases remain nonmetallic up to 7 TPa.

Abstract

We propose three new phases of H2O under ultrahigh pressure. Our structural search was performed using an adaptive genetic algorithm which allows an extensive exploration of crystal structure. The new sequence of pressure-induced transitions beyond ice X at 0 K should be ice X - Pbcm - Pbca - Pmc21 - P21 - P21/c phases. Across the Pmc21 - P21 transition, the coordination number of oxygen increases from 4 to 5 with a significant increase of density. All stable crystalline phases have nonmetallic band structures up to 7 TPa.