A comparative study of small 3d-metal oxide (FeO)n, (CoO)n, and (NiO)n clusters

Geometrical and electronic structures of the 3d-metal oxide clusters (FeO) n , (CoO) n , and (NiO) n are computed using density functional theory with the generalized gradient approximation in the range of 1 ≤ n ≤ 10. It is found that the cluster geometries are similar in the (FeO) n and (CoO) n series but noticeably different in the (NiO) n series for several values of n . All of the lowest total energy states are found to possess relatively small spin multiplicities and are either antiferromagnetic or ferrimagnetic except for the states of (NiO) 3 , (NiO) 4 , (NiO) 9 , and (NiO) 10 , which are ferromagnetic. The computed polarizabilities per atom undergo a steep decrease when compared to the atomic values of the MO monomers (M = Fe, Co, and Ni). Surprisingly, the polarizability does not strongly depend on either M or n in all the considered series when n varies from 3 to 10. The binding energies per atom are the largest in the (FeO) n series, followed by the binding energies of (CoO) n and (NiO) n . Geometrical and electronic structures of the 3d-metal oxide clusters (FeO) n , (CoO) n , and (NiO) n are computed using density functional theory with the generalized gradient approximation in the range of 1 ≤ n ≤ 10.