Embedded atom model calculations of the structures of small Ni clusters and of a full Ni monolayer on the (001) surface of Al

Abstract

Using the Voter and Chen embedded-atom model potential for the Ni—Al system, we performed quenched molecular dynamics simulations to obtain the structures and binding energies of small clusters and of a full monolayer of Ni atoms on the AI(001) surface. Our results show that both clusters an.d the mono-layer undergo surface alloying, i.e., there is a tendency for the Ni atoms to be embedded in the substrate, displacing Al atoms from their initial positions. However, whereas the surface alloying of the clusters occurs rapidly, that of the monolayer requires an appreciable prior equilibration period at a temperature allowing atomic mobility; quenching without this equilibration period can freeze the system in a metastable state in which the Ni adlayer remains on an Al surface that. is hardly altered. An analogous metastable state may have been achieved in experiments by other authors with ultrathin Ni films.