Structures and magnetic moments of Nin (n=10∼60) clusters

We have studied the stable geometries of Ni-n clusters using the first principles method with ultrasoft pseudopotentials. It is found that the ground state structures of Ni-n(n = 10 similar to 27, 41 similar to 56) are icosahedron-like, while Ni-13 and Ni-55 are perfect icosahedra, in agreement with experimental results. For Ni-n (n = 28 similar to 40), no simple growth mode can be found even though some of them display certain symmetry. The size dependence of magnetic moments calculated with these ground state structures nicely reproduces experimental trend. In general, we found two peaks around n = 15 similar to 20 and n = 35 similar to 40, and three dips at n = 13, 34, 55. The deviation between the calculated results and experimental data, assigned as the orbital magnetic moment, decreases monotonically as the cluster size increases. (c) 2006 Published by Elsevier B.V.