Ab initio calculations of Fe-Ni clusters

The clusters of Fe, Ni, and Fe-Ni are investigated computationally using a density functional approach. The geometries of clusters are optimized under the constraint of well-defined point group symmetries at the UB3LYP/LanL2DZ level. The equilibrium geometries and binding energies are presented and discussed, together with natural populations and natural electron configurations. In addition, the binding energies of Fe(n-x)Ni(x) clusters are found to generally decrease by successive substitutions of Ni atoms for Fe atoms. For Fe(n-x)Ni(x) clusters, the comparisons on total energies between isomers indicate that Ni atoms energetically prefer clustering in the mixed Fe-Ni clusters. The calculations for Fe(n-x)Ni(x) clusters show that the clustering leads to a segregation of Ni atoms from Fe atoms. (C) 2009 Elsevier B.V. All rights reserved.