Comparative ab initio study of the structural, electronic, and magnetic trends of isoelectronic late 3d and 4d transition metal clusters

We present a density-functional comparative study of the electronic properties and the structural trends of the late isoelectronic 3d (Fe, Co, Ni) and 4d (Ru, Rh, Pd) free-standing transition metal clusters of 13 and 23 atoms. Different types of structures have been analyzed: compact arrangements such as icosahedral shape, open arrangements such as the cubic ones, and structures reminiscent of the crystal lattices. We have calculated total-energy differences between the structural and the spin isomers, as well as the electronic charge and spin-moment distribution within the clusters. We have found that some structural trends correlate with electronic trends, which are consistent with the spectrum of the single atoms in the dn s1 configuration (n=7,8,9 for Fe and Ru, Co and Rh, and Ni and Pd, respectively). We have also found that magnetism plays a role in the Fe clusters. The exceptions found in some clusters, which depart from the structural trend obtained for their respective 3d or 4d family, illustrate the complexity of the bond formation in transition metal systems in which the itinerant but localized d electrons coexist with the delocalized sp electrons in the valence states. © 2008 The American Physical Society.

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