Symmetry-based electronic structures of superatoms: beyond the jellium model

Abstract In the early stages of introducing the term superatom to describe atomic clusters exhibiting chemical properties similar to periodic table elements, the electronic structures of these clusters were understood through simplified calculations based on the jellium model with spherical potential. Against this backdrop, a superatomic physical image based on the sequence of electronic energy levels predicted by the model was formed. In this work, the analysis of the development of superatoms first indicates that, due to their non-ideal spherical structures, density functional theory calculations that take into account realistic atomic potential without relying on the simplified jellium sphere model can yield more reliable results. Although the electronic structure of some single-element atomic clusters under this calculation may agree with the results of jellium model, their orbitals with the same angular momentum actually split. Moreover, in more complex multi-element systems, the sequence may change further. Nevertheless, these systems still maintain well-defined electronic shell structures, allowing them to be classified as superatoms. This work also verifies these findings through calculations of specific stereoscopic, planar and compressed superatoms. Thus, superatoms intrinsically surpass the results from the jellium model approximation, the realistic atomic potential provides more detailed insights into their electronic structures. This finding will contribute to both fundamental and applied research of superatoms.