Point defects on oxide surfaces were presumed to be preferential nucleation sites for supported metal clusters. Under typical growth conditions, dimers constitute the first step in island nucleation. First-principles calculations on the formation of Pd dimers on regular and defect sites of the MgO(100) surface showed that nucleation occurred with large dimer binding energies at divacancies and charged O vacancies (F+ centers), while it was less favorable on steps and neutral F centers. The extensive database of defect trapping/attachment properties gives a firm basis to rationalize recent atomic-force microscopy findings and provided guidelines valid, in general, for ionic substrates.

Nucleation of Pd Dimers at Defect Sites of the MgO(100) Surface. L.Giordano, C.Di Valentin, J.Goniakowski, G.Pacchioni: Physical Review Letters, 2004, 92[9], 096105 (3pp)