Atomic relaxation of Ag and Cu on fcc(100) and (110) surfaces

In this work we investigated the atomic relaxation in copper and silver substrates. The system surfaces are oriented following (100) and (110) directions. The relaxation and the bond length variation are only by the mutual atomic interaction. The all calculations are made at zero Kelvin in order to neglect the thermic vibration of the substrate atoms. The (100) surfaces are more compact than (110) ones, which is clearly observed in the inter-layer relaxation rate. On the other hand, the investigation of the adatom relaxation in the case of eterosystems (Cu/Ag) reveals that Cu adatom tends to penetrate through the surface which corresponds to the exchange process. In contrast, the Ag adatom on Cu surface attempts to be far from the surface giving a preferential occurrence to the jump process on the surface. This finding is confirmed by the binding strength or binding energy calculations where we have found (for (100) surface as example) that Cu-Ag is 2.30 and 2.09 eV for Cu/Ag and Ag/Cu, respectively