CNDO calculations of nickel atom clusters

CNDO molecular orbital calculations for nickel atom clusters containing from one to thirteen atoms in various geometric arrangements are presented. The parameters were selected so that an octahedral Ni₆ cluster had an equilibrium inter-nuclear distance, d band occupancy, binding energy, Fermi level, and d band width approximating those of bulk nickel. For clusters with a given number of atoms the stability always increased in the order linear < planar < three-dimensional cluster. The general assumption that the binding energy per atom in metal clusters is proportional to the number of nearest neighbours is supported by these CNDO calculations although this relation is certainly not exact for small clusters. Examination of the calculated orbitals does not indicate a separation of the d band into one part made up from atomic t_2g orbitals and another from e_g orbitals. Overall the CNDO method appears to present a reasonable approach to calculating properties of small metal clusters.