Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 43: Frontiers of Electronic Structure Theory: Focus on Artificial Intelligence Applied to Real Materials 1
O 43.6: Vortrag
Mittwoch, 7. September 2022, 11:45–12:00, S054
The first-principles phase diagram of monolayer nanoconfined water — •Venkat Kapil1, Christoph Schran1, Andrea Zen2, Ji Chen3, Chris Pickard1, and Angelos Michaelides1 — 1University of Cambridge, UK — 2Universitá di Napoli Federico II, Italy — 3Peking University, Beijing, China
Water in nanoscale cavities is ubiquitous and of central importance to everyday phenomena in geology and biology, and at the heart of current and future technologies in nano-science. A molecular-level picture of the structure and dynamics of nano-confined water is a prerequisite to understanding and controlling the behavior of water under confinement. Here we explore a monolayer of water confined within a graphene-like channel using a framework that combines developments in high-level electronic structure theory, machine learning, and statistical sampling. This approach enables a treatment of nano-confined water at unprecedented accuracy. We find that monolayer water exhibits surprisingly rich and diverse phase behavior that is highly sensitive to temperature and the van der Waals pressure acting within the nano-channel. Monolayer water exhibits numerous molecular ice phases with melting temperatures that vary by over 400 degrees in a non-monotonic manner with pressure. In addition, we predict two unexpected phases: a *hexatic-like* phase, which is an intermediate between a solid and a liquid, and a superionic phase with a high electrical conductivity exceeding that of battery materials. Our work suggests that nano-confinement could be a promising route towards superionic behaviour at easily accessible conditions.