Three-Shell Icosahedral Superatoms In[TM₁₃@Bi₂₀]^-（TM=3d, 4d Transition-metal Atoms）Clusters:a First-Principles Prediction

Recent studies have found that some clusters with specific size, composition, structure and total charge are particularly stable. Such novel clusters, named as the "superatoms", can mimic elemental atoms in the periodic table. On the one hand, people can design various types of superatoms, to mimic or alternatives the various kinds of atoms in the traditional periodic table (atomic properties mainly rely on the changes of number of electrons), and to construct a three-dimensional or multidimensional periodic table by adjusting the adjustable parameters of superatom (atomic properties will depend on the effective parameter of system’s composition, concentration and total charge …). On the other hand, the superatoms offer the prospect of serving as the new building blocks of nanomaterials because of its stable physical and chemical properties, the structure, mimic free atom. We can design functional materials with unique morphology and novel properties. Superatoms exhibit novel properties and potential application value, inspire people’s extensive research enthusiasm.In this article, we design nearly spherical [TM13@Bi20] clusters with three layers of core-shell structure by placing icosahedron TM13(TM=3d,4d) clusters into the dodecahedron Bi2o cage. Using the density functional theory (DFT) under the frameworks of the generalized gradient approximation (GGA), we perform a systemically research on the stability, electronic structure and magnetic properties of [TMi3@Bi20] clusters. The results obtained can be summarized as followings:(1) we design [TM13@Bi20]-(TM=3d,4d) clusters with core-shell structure of high spherical symmetry, then perform a systemically research on the binding energy, embedding energy, HOMO-LUMO gap, electron affinity (EA) and so on. We found that most TM13 species can be stably embedded into Bi2o cage except for Zni3 and Cd13, Ti13 and Ru13 clusters are the most suitable doping counterpart. (2) Owning to icosahedral ligand field of [TM13@Bi20]- structure, the molecular orbitals within a high angular momentum that is more than 5-fold degenerate and labeled by F, G, H … will split into a set of sub-orbitals. The spatial shapes of each molecular orbital resembles the corresponding atomic orbital, it reflects the clusters our designed have the basic characteristics of superatom. (3) Partial [TM13@Bi20]- clusters posses giant magnetic moments, the exchange-splitting in TM-d states is the driving force for the exchange-splitting of superorbitals (D, G, H) with high quantum number. (4) The electron filling forms of nonmagnetic [Sc13@Bi20]- and [Y13@Bi20] clusters are similar to magnesium, so they can simulate magnesium. [Mn13@Bi20]- is a ideal magnetic superatom because of its high physical and chemical stability and giant magnetic moment of 36 uB.