Structure of small Nin (n≤8) clusters

Density functional theory B3LYP are performed in study on structure of Nin, Nin+ and Nin- (n=2-8). DGDZVP all-electron basis sets and TZVP all-electron basis sets are employed. Equilibrium geometries, ionization potentials, electron affinities and binding energies are obtained. It shows that the ground state of Ni2, Ni3, Ni4, Ni5 and Ni6 cluster are 5-, 7-, 9-, 11-, and 13-multiple state, respectively, which indicates spin polarization effect in Nin(n≤8) clusters is important. That is, there are 4, 6, 8, 10, and 12 parallel spin electrons in Ni2, Ni3, Ni4, Ni5 and Ni6 cluster, respectively. Number of non-conjugated electrons in ground state cluster is the greatest. These electrons occupy different spacious orbitals so that energy of Nin(n≤8) cluster is minimized. It can be concluded that effect of parallel spin in Nin(n≤8) clusters is greater than effects of conjugated clusters, which is obviously related to electron d delocalization. This is spin polarization effect of Nin (n≤8) clusters, which is a result of the Hund's rule. Moreover, we find that spin magnetic moments of Nin(n=6-8) are 8μB, those of Nin+(n=6-8) are 9 μB and those of Nin- (n=4-10) are 7 μB. © 2012 Chinese Nuclear Society.