Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 91: Epitaxy and growth: Oxides and insulators

O 91.3: Talk

Thursday, March 17, 2011, 17:45–18:00, WIL C307

Termination of the hexagonal ice (0001)-surface by admolecule structures — •Anja Michl and Michel Bockstedte — Lehrstuhl Theoretische Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr 7B2, 91058 Erlangen

Ice grown on metal substrates exhibits a wide range of structures including clusters of varying shape, amorphous and crystalline islands owing to the flexibility of the water bond network and the nature of the water-metal interaction. Focusing on crystalline ice, recent experiments (e.g. [1,2]) have shown that ice (0001)-surface areas are terminated by water admolecule structures rather than by the bi-layer. In particular detailed high-resolution STM-experiments [2] of ice islands grown on Cu(111) analyzed the arrangement of admolecules on top of the bi-layer. Here we address the interaction of admolecules on this surface that eventually leads to the observed admolecule structures theoretically with an ab initio method. We find that admolecules coalesce into a nominal (2x1) superstructure forming mutal hydrogen bonds. Furthermore hexagonal rows of admolecules can interact with additional admolecules. The energetics of such structures much depend on the arrangement of dangling OH-groups and the bonding of the row edge to the underneath bi-layer. Undercoordinated edge molecules are found to evolve to the top of the row to enhance their own coordination.

[1] Ph. Parent et al., J. Chem. Phys. 117, 10842 (2002).

[2] M. Mehlhorn and K. Morgenstern, Phys. Rev. Lett. 99, 246101 (2007).