Atomic arrangements in Ni7 and Ni8 clusters

First principles electronic structure studies of geometries, binding energies, and magnetic moment of Ni-7 and Ni-8 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 Ni-7 cluster is found to be a capped octahedron while that of Ni-8 is a D-2 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 N-2 adsorption experiments. Calculated magnetic moments and ionization potentials are compared with recent experiments. (C) 1998 Published by Elsevier Science B.V. All rights reserved.