Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 26: Oxides and Insulator Surfaces: Adsorption

O 26.3: Poster

Montag, 7. März 2016, 18:15–20:30, Poster E

Coverage-dependent behaviour of water on hematite(0001) from first principles — •Roman Ovcharenko and Elena Voloshina — Humbold-Universität zu Berlin, Berlin, Germany

It is well established that the water adsorption behaviour at high coverage regime may differ drastically from its adsorption at low coverage. The hydrogen bond network between polar water molecules and their residues tends to stabilize the water layer structure on top of a surface preventing following dissociation. Thus, the qualitative changes from the dissociative adsorption to the molecular one were found to take place on top of the aluminium oxide (0001) surface, which is isomorphic to hematite, at coverage more than 1 ML. For magnetite(001) such mixed dissociative-molecular adsorption was established already for the second water molecule in the 2x2 unit cell. Partially inheriting the properties of both aforementioned metal oxides, the hematite surface may affect the upper water layers forcing them to demonstrate adsorption behaviour different to the one on aluminium oxide or magnetite.

Here we present the theoretical study of the water adsorption on top of the hematite(0001) single-iron termination within the PBE+U+D level of accuracy to account for both the Fe 3d strongly correlated electrons as well as the weak dispersion interactions between water fragments on top of the surface.