A molecular dynamics investigation of surface reconstruction on magnetite (001)

Molecular dynamics calculations using analytical potential functions with polarizable oxygen ions have been used to identify a novel mode of reconstruction on the half-occupied tetrahedral layer termination of the magnetite (Fe3O4) (001) surface. In the proposed reconstruction, the twofold coordinated iron ion in the top monolayer rotates downward to occupy a vacant half-octahedral site in the plane of the second-layer iron ions. At the same time, half of the tetrahedral iron ions in the third iron layer are pushed upward to occupy an adjacent octahedral vacancy at the level of the second-layer iron ions. The other half of the third-layer iron ions remain roughly in their original positions The proposed reconstruction is consistent with recent low-energy electron diffraction and X-ray photoelectron spectroscopy results. It also provides a compelling interpretation for the arrangement of atoms suggested by high-resolution scanning-tunneling microscopy studies. (C) 1999 Published by Elsevier Science B.V. All rights reserved.