Generalized simulated annealing studies on structures and properties of Ni-n (n=2-55) clusters

With the generalized simulated annealing algorithm (GSA), the structures an d properties of Ni-n (n = 2-55) clusters have been studied. We find that be sides the icosahedral-like structure, the structures of Ni clusters can be decahedral-like or fragments of the fee crystal. The clusters with n = 13, 38, 55 are found to be very stable. With modification of the effective coor dination number model, the calculated ionization potentials of Ni clusters are in good agreement with the experimental data. The dynamical simulations show that the clusters with a closed-compact inner core have a high vibrat ional frequency mode, while the disordered clusters show some low vibration al frequency modes.