Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 96: Structure of Solid/Liquid Interfaces II

O 96.8: Talk

Friday, March 11, 2016, 12:15–12:30, S052

Mapping the stabilities of two-dimensional water polymorphs using dispersion-corrected DFT — •Tanglaw Roman and Axel Groß — Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany

The properties of the contact layer of water or ice on solid surfaces are still not fully understood. The questions that require answers include: How ice-like is water close to a solid surface? How realistic are hexagonal bilayer-based models in describing interfaces with water, both on hexagonal close-packed surfaces and on surfaces of other symmetries? How dense is water at these interfaces? What is the most stable form of ordered water in two dimensions? How different is 2D from 3D crystalline water, and how does the transition go? Which physical factors may contribute to the formation of a water lattice with another symmetry? In response to these, we present a systematic sweep of structural possibilities of water in two dimensions using density functional theory with dispersion corrections, screening one and two-layer structures over different symmetries. Starting with free-standing models, calculations yield structures that differ from those previously reported using classical molecular dynamics, and include several structures which we find more stable than the traditional hexagonal bilayer. Results are discussed with respect to observed water structures confined within graphene sheets, and on how these impact our understanding of water structures at solid surfaces of varying symmetries and interaction strengths.