Deposition of copper clusters on the Cu(1 1 1) surface

Results of a theoretical study of collision processes are reported. The relation between the impact energy for the deposition of copper clusters (with N = 13, 18, 38, and 55 atoms) on the Cu(1 1 1) surface and the structural and energetic stability of the products is investigated by means of molecular dynamics simulations. The interatomic interactions are described with a potential from the embedded atom method (EAM) family. The roles of the impact energy and cluster size are studied. It is shown that larger clusters change their structure less than smaller clusters, whereas the smaller (magic) Cu13 and (non-magic) Cu18 clusters lose rapidly their similarity to the original clusters for not too small impact energies. Moreover, for an impact energy of 0.5 eV/atom the structure of these clusters shows the lowest similarity to the original structures. In this case, the Cu18 cluster forms a monolayer on the surface, with one atom of the surface substituted by an atom from the cluster, while the Cu13 icosahedron forms a slightly deformed monolayer. Only at this impact energy monolayers can be formed. Instead, increasing the impact energy leads to a symmetrical pyramidal product for Cu13 and to a double-layered cluster for Cu18. On the other hand, even at an impact energy of 0.9 eV/atom the final products of the larger fcc Cu38 and the icosahedral Cu55 clusters contain two, and three layers, respectively, on the surface.