Geometries, stabilities, and electronic properties of (n=9–16) clusters: Density-functional theory investigations

Fe-doped germanium clusters have been systematically investigated by using the density-functional approach. It was found that doping of one Fe atom contributes to strengthening the stability of the germanium framework. Maximum peaks of the fragmentation energies, the second-order energy differences, and the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO–LUMO) gaps were observed for clusters of sizes n = 9, 11, 13, 14, and 16, implying their relative higher stability than other-sized FeGen clusters. In addition, the strongest stability of FeGe14 might stem from its highest symmetry (Oh). The HOMO–LUMO gaps are obviously reduced when the Fe atom is doped into the Gen clusters. We also found that charge always transfers from iron to germanium atoms in all sized FeGen clusters and the magnetic moment of the Fe atom does not quench when embedded in large-sized Gen (n = 10, 11, 12, and 16) clusters.