Probing the geometry of copper and silver adatoms on magnetite: quantitative experiment versus theory

M. Meier, Z. Jakub, J. Balajka, J. Hulva, R. Bliem, P. K. Thakur, T-L Lee, C. Franchini, M. Schmid, U. Diebold, F. Allegretti, D. A. Duncan, G. S. Parkinson

University of Vienna, Faculty of Physics and Center for Computational Materials Science, 1090 Vienna, Austria
Institut für Angewandte Physik, TU Wien, 1040 Wien, Austria
Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0QX UK
Physics Department E20, Technical University of Munich, 85748 Garching, Germany

Nanoscale 10 (2018) 2226-2230

Accurately modelling the structure of a catalyst is a fundamental prerequisite for correctly predicting reaction pathways, but a lack of clear experimental benchmarks makes it difficult to determine the optimal theoretical approach. Here, we utilize the normal incidence X-ray standing wave (NIXSW) technique to precisely determine the three dimensional geometry of Ag1 and Cu1 adatoms on Fe3O4(001). Both adatoms occupy bulk-continuation cation sites, but with a markedly different height above the surface (0.43 ± 0.03 Å (Cu1) and 0.96 ± 0.03 Å (Ag1)). HSE-based calculations accurately predict the experimental geometry, but the more common PBE + U and PBEsol + U approaches perform poorly.

Corresponding author: David A. Duncan. Reprints also available from Gareth Parkinson (parkinson at iap_tuwien_ac_at).

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