Competing mechanisms in the atomic diffusion of a MgO admolecule on the MgO(001)surface

Abstract

The diffusion mechanism of a MgO admolecule on a flat MgO(001) surface has beeninvestigated by equilibrium molecular dynamics simulation. Care has been taken in thechoice of the phenomenological interionic potential used. Four distinct mechanisms havebeen found and the corresponding dynamical barriers determined at high temperature.Some static barriers have also been computed for comparison and all intermediateconfigurations have been obtained with the same phenomenological potential and also bythe DFT-GGA approach. The hopping mechanisms involving the Mg adatom,although dominant, must be combined with the infrequent mechanisms involvingdisplacements of O adatoms in order to provide the mass transport on the surface,which is crucial for crystal growth both in the nucleation and step-flow regimes.