Oxidation and diffusion processes at the Mn-doped Fe(0Â 0Â 1) and Fe(1Â 1Â 0) surfaces from first-principles

► The presence of Mn in the Fe surface layer does not favour the O adsorption. ► The energy barriers for O, Fe or Mn diffusion are lower on Fe(1 1 0) than on Fe(1 0 0). ► On the Fe(0 0 1) termination, the Mn and O adatoms are more mobile than Fe. ► On the Fe(1 1 0) termination, the Mn adatom is much more mobile than O and Fe. ► The formation of MnO (resp. FeO) from adatoms is exothermic (resp. endothermic).