PHYSICS OF NICKEL CLUSTERS - ENERGETICS AND EQUILIBRIUM GEOMETRIES

The equilibrium geometries and the binding energies of Ni-n clusters ( n less than or equal to 23) have been calculated by using an empirical many-body potential and molecular dynamics (MD) simulation, For small clusters, the potential is found to reproduce the geometries based on first-principles density functional calculations. It is shown that th e clusters do not mimic the bulk structure and undergo significant geo metrical changes with size. The binding energy per atom, on the other hand, increases monotonically with size. The evolution of the geometri es is found to be correlated with the underlying changes in the nature of bonding. An analysis of the fragmentation channels based on the gr ound state energies shows the loss of the Ni dimer to be the most ener getically favorable channel. The calculated geometries are compared wi th those derived from recent experiments on N-2 adsorption on Ni-n clu sters.