STRONG RELAXATIONS AT THE CR2O3(0001) SURFACE AS DETERMINED VIA LOW-ENERGY-ELECTRON DIFFRACTION AND MOLECULAR-DYNAMICS SIMULATIONS

The surface structure of Cr2O3(0001) was investigated by quantitative low-energy electron diffraction and molecular dynamic simulations. In qualitative agreement with each other, both methods indicate strong ve rtical relaxations at and near the surface. These relaxations are conc omitant with a charge reduction and depolarization, which stabilize th e surface, yielding energies close to those found for non-polar oxide surfaces with non-divergent surface potentials. The lateral arrangemen t of oxygen atoms is identical to that in the bulk, i.e. there are no lateral distortions to accomodate the strong interlayer relaxations. T he latter extend deep into the surface, with the experimentally determ ined changes of the first four interlayer distances being -38%, -21%, -25% and +11% with respect to the unrelaxed bulk values.