Geometry and electronic structures of magic transition-metal oxide clusters M9O6 (M = Fe, Co, and Ni)

The magic oxide clusters M9O6 (M = Fe, Co, Ni) are found by using reactive laser vaporized cluster source. From the first-principles calculations, the possible equilibrium geometries for these three oxide clusters are determi ned to be a C-2 nu symmetry, where the skeleton composed of 9 metal atoms a lso has C2(nu) symmetry, different from the equilibrium structures of pure transition metal cluster M-9. The O atoms are energetically more favorable to cap the triangle surfaces. In Fe9O6 and Co9O6 clusters, oxygen atoms are antiferromagnetically polarized while ferromagnetically polarized in the N i9O6 cluster, Similar to the case of O atoms adsorbed on the reconstructed Ni(110) surface. The magnetic behaviors are explained from electronic struc tures.