The structure and dynamics of noble metal clusters.
Murrell-Mottram empirical atomistic many-body and Gupta n-body potentials have
been used to study various aspects of the cluster chemistry of copper, silver, gold and
nickel. Simulated annealing techniques have been used to search for the global minima
of the four metals with up to 55 atoms. Icosahedral, decahedral, octahedral, hexagonal
closed packed and hexagonal prismatic structures were found. The gold clusters
show some rearrangements and distortions from ideal geometries. Polyhedral cluster
calculations up to 1 500 atoms predict that icosahedra and truncated octahedra are
particularly stable. Calculations on the structures of copper-gold alloy clusters show
that gold atoms prefer to occupy the surface of the cluster. A simple approximation
to model the passivation of gold clusters by thiol ligands predicts that for 55 atoms
the passivated cuboctahedron is more stable than the icosahedron, the reverse of the
order for the bare clusters. Molecular dynamics simulations of gold adatoms on the
gold (111) surface and of the impact of a 55 atom gold cluster with the gold (111)
surface have been performed.