Structural and magnetic properties of Nin (n = 2–21) clusters

Extensive studies of structural and magnetic properties of pure Nin (n=2–21) clusters are carried out using density functional theory with generalized gradient approximation. A new structural growth pattern is reported and the icosahedron sequence is not the global minima structures for size n < 16. The evolution pattern of Ni5–Ni10 clusters is based on square pyramid. For cluster between n = 9 and n = 14, structures of them are trilayered stacking pattern. Especially for Ni13, it seriously deviates from icosahedral pattern which was frequently assumed in previous studies. Ni10, Ni13 and Ni14 are pieces of a double tetrahedron. For cluster size larger than 16, icosahedron based configurations are found to be the dominative structure pattern with exception of Ni19. But trilayered structure is a strong competitor due to small difference in energy between this pattern and icosahedral family. The comparison of magnetic behavior between the calculations and experimental results are conducted. The average coordination mainly dominates on the magnetic behavior in the size range we considered.