Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 86: Oxides and Insulators: Adsorption
O 86.1: Talk
Friday, February 29, 2008, 09:30–09:45, MA 141
Water Adsorption on Fe3O4(001): A First Principles Study — •Narasimham Mulakaluri1, Rossitza Pentcheva1, Wolfgang Moritz1, and Matthias Scheffler2 — 1Section Crystallography, Dept. for Earth and Environmental Sciences, University of Munich — 2Fritz-Haber-Institut der MPG, Berlin
The mode of adsorption of water (dissociative versus molecular) as well as its effect on the structural and electronic properties of the Fe3O4(001) surface is studied using density functional theory (DFT) calculations with the FP-LAPW method in the WIENK2k implementation. We vary the concentration of water and hydroxyl groups starting from a single water molecule per (√2× √2)R45∘ unit cell and compare the surface stability of the different terminations as a function of the O2 and H2O partial pressure within the framework of ab-initio thermodynamics. Over a substantial range above the oxygen and water poor conditions, a clean Jahn-Teller distorted bulk termination is most favorable (modified B-layer) [1]. With increasing water pressure a water monomer, parallel to the surface, and finally a fully hydroxylated B-layer is stabilized. The calculations give indications of a lifting of the (√2× √2)R45∘-reconstruction upon hydroxylation, consistent with low energy electron diffraction (LEED) measurements.
[1] R. Pentcheva et al., Phys. Rev. Lett. 94,126101 (2005).