Evolution of geometrical structures, stabilities and electronic properties of neutral and anionic Nbn−1Co (n = 2–9) clusters: Comparison with pure niobium clusters

The structural evolution, relative stability, electronic and magnetic properties of neutral and anionic Nbn−1Co (n = 2–9) clusters have been investigated systematically using the density functional theory at BP86 level. The results showed that most of the isomers are likely to form three-dimensional structures, resembling those of the pure niobium clusters. By calculating the binding energies, fragmentation energies, second-order difference of energies and HOMO–LOMO energy gaps, Nb4Co, Nb4Co−, Nb6Co and Nb6Co− clusters were found to have stronger relative stabilities and more enhanced chemical stabilities. Meanwhile, the patterns of HOMOs were analyzed to gain insight into the bond nature of the clusters. The natural population analysis reveals that the electrons transfer from Nb frames to Co in neutral Nbn−1Co clusters and the negative charges localized on Co atoms have an increasing tendency with the increment of cluster size. What’s interesting, we found a total quenching of the cobalt magnetic moment in the neutral Nb7Co cluster.