Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 56: Oxide Surfaces I
O 56.10: Vortrag
Mittwoch, 13. März 2013, 18:15–18:30, H45
Adsorbed water structures on alkaline earth metal oxide (001) surfaces at realistic conditions: A first-principles study — •Xunhua Zhao, Eric Huynh, Sergey V. Levchenko, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin-Dahlem 14195, Germany
Understanding the interaction between water and oxide surfaces is of fundamental importance for basic and engineering sciences. Recently, one-dimensional structures have been observed on CaO(001) in the presence of H2O [1]. Such structures have not been reported so far for MgO and SrO. We performed a free-energy-based ab initio genetic algorithm and atomistic thermodynamics analysis to find stable structures of water adsorbed on MgO(001), CaO(001) and SrO(001). The structures were searched without stoichiometric constraints. Density-functional theory with semilocal (PBE) and hybrid (HSE06) exchange-correlation functionals with a first-principles dispersion interaction correction was employed. Our results confirm the presence of a range of H2O chemical potentials around the experimental conditions (T = 300 K, pH2O = 10−9 atm) where one-dimensional adsorbed water structures are preferred on CaO(001). Trends in the range of stability and conditions for one-dimensional versus monolayer structures on MgO(001), CaO(001), and SrO(001) will be discussed and related to differences in the electronic structure of the oxides. The accuracy of the functionals is analyzed based on the “exact-exchange plus correlation in the random-phase approximation” approach.—[1] X. Shao, N. Nilius, M. Sterrer, Y. Fujimori, and H.-J. Freund, to be published.