A combined DFT/LEED-approach for complex oxide surface structure determination:: Fe3O4(001)

A combination of density functional theory (DFT) calculations and low energy electron diffraction (LEED) analysis is used to determine the surface structure of Fe3O4 0 00). We find that the surface is rich in oxygen and the observed (root 2- x root 2-)R45 degrees reconstruction is a result of a Jahn-Teller distortion as established by recent DFT-calculations [R. Pentcheva, F. Wendler, H.L. Meyerheim, W. Moritz, N. Jedrecy, M. Scheffler, Phys. Rev. Lett. 94 (2005) 126101]. The corresponding Pendry reliability factor is 0.34. Furthermore, we investigate the influence of the preparation conditions (temperature, oxygen pressure) on the LEED intensities of natural and synthetic samples. The electron scattering phase shifts used in the analysis of the LEED spectra are derived from two methods, one based on the DFT electron densities and another employing an overlap of atomic potentials with optimized muffin-tin radii. Both approaches lead to similar results. (c) 2008 Elsevier B.V. All rights reserved.