Energetics of surface alloying:3dadatoms on the Au(100) surface

Ab initio studies of energetics of surface alloying on an atomic scale are presented. We demonstrate that site exchanges between $3d$ transition metal impurities on the Au(100) surface and Au atoms are energetically favorable. These results show that models of epitaxial growth based on an abrupt boundary between components can be inadequate for all $3d$ transition metal nanostructures on the gold surface. Consideration based on the energetics of impurities in the gold surface leads to the conclusion that a random distribution of isolated impurities is expected in all systems investigated.