Molecular-dynamics study of the structures, binding energies, and melting of clusters of fcc transition and noble metals using the Voter and Chen version of the embedded-atom model.

Abstract

Using the Voter and Chen version of the embedded-atom model, we have carried out molecular-dynamics simulations to study the structures and melting of Ni, Pd, Pt, Cu, Ag, and Au clusters in the size range N=2--23. The model predicts that all these clusters have structures based on icosahedral packing and similar thermodynamic behavior. Salient results are that all the 13-atom clusters have high melting temperatures, and that a premelting phenomenon occurs in the 14-atom and 20-atom clusters, which have a single atom outside a very stable structural core. Specific studies for Ni demonstrate that the premelting phenomenon also occurs in ${\mathrm{Ni}}_{15}$, ${\mathrm{Ni}}_{16}$, and ${\mathrm{Ni}}_{17}$, which have, respectively, two, three, and four atoms outside the ${\mathrm{Ni}}_{13}$ core.