Global lowest energy structures and electronic properties of InnM (M = Mn, Fe, Co, Ni, n = 6–9) clusters

The global lowest-energy structures of the transition metal (TM) doped In_nM (M = Mn, Fe, Co, Ni, n = 6–9) clusters are studied by using genetic algorithm combined with spin-polarized density functional theories. The low energy structures suggest that the basic building units of In_nM in this size range are TM doped triangular prism and octahedron. For the lowest energy isomers, the TM atoms are endohedrally doped in In₈Co/Ni and In₉Fe and exohedrally doped in other clusters. Charge density analysis shows that Mn atom offers electron to the In_n frames but Co and Ni accept electrons. The spin multiplicities of the lowest energy structures are the same with those of the TM atoms for the exohedrally doped In_nM clusters for n = 6, 8, and the values are smaller by one for the endohedrally doped clusters. The molecular orbitals and density of states reveal that the 4s² electrons of the TM atoms and the 5s²5p valence electrons of the In atoms form superatomic orbitals consistent with the jellium model, but the 3d orbitals of the TM interact with the superatomic orbitals in different manners and are generally singly occupied.

Graphical Abstract