Atomic arrangements in Ni7 and Ni8 clusters

First principles electronic structure studies of geometries, binding energies, and magnetic moment of Ni7 and Ni8 clusters have been carried out within a density functional scheme. Several geometries and the possible Jahn–Teller distortions were examined. The ground state of a Ni7 cluster is found to be a capped octahedron while that of Ni8 is a D2 bisdisphenoid. In each case, the ground state has energetically close states with different geometries but same magnetic moment. Some of these geometries correspond to structures observed in N2 adsorption experiments. Calculated magnetic moments and ionization potentials are compared with recent experiments.