Bottom-up design and assembly with superatomic building blocks

Constructing specific structures from the bottom up with artificial units is an important interdisciplinary topic involving physics,chemistry,materials,and so on.In this work,we theoretically demonstrated the feasibility of using superatoms as building blocks to assemble a complex at atomic-level precision.By using a series of actinide-based endohedral metallofullerene(EMF)superatoms that can form one,two,three and four chemical bonds,a planar complex with intra-and inter-molecular interactions was assembled on the Au(111)surface.This complex is composed of two parts,containing ten and eight superatoms,respectively.The electronic structure analysis shows that the electron density inside each part is connected and the closed-shell electronic arrangement system is designed.There is also an obvious van der Waals boundary by physical adsorption between the two parts,and a stable complex is formed.Since this complex is realized by the first-principles calculations of quantum mechanics,our results help not only achieve atomic-level precision construction with artificial superatomic units but also maintain atomic-level functional properties.

Mandrel degradation model of combined fast and slow processes

In this paper, we report the study of degradation for a kind of ideal mandrel material called poly-α-methylstyrene based on theoretical and experimental methods. First-principles calculations reveal two types of process: depolymerization and hydrogen-transfer-induced chain scission. The energy barrier for the former(0.68–0.82 eV) is smaller than that for most of the latter(1.39–4.23 eV). More importantly, reaction rates suggest that the former is fast whereas the latter is mostly slow, which can result in a difference of 5–31 orders of magnitude at 550 K. Furthermore, a thermogravimetric experiment shows that the activation energy of 2.53 eV for degradation is between those of fast and slow processes,corresponding to the theoretical average value of multiple reaction paths. Thus, a mandrel degradation model combining fast and slow processes is established at the atomic level. Our work provides a direction for research into the key technology of target fabrication in inertial confinement fusion.

Direct assembly between closed-shell coinage metal superatoms

Bottom-up constructing all-metal functional materials is challenging,because the metal clusters are prone to lose their original structures during coalensence.In this work,we report that closed-shell coinage metal superatoms can achieve direct chemical bonding without losing their electronic properties.The reason is that the supermolecule formed by two superatoms has the same number of bonding and anti-bonding supermolecular orbitals,in which the bonding orbitals contribute to bonding and the antibonding orbitals with anti-phase orbitals delocalized over each monomer to maintain the individual geometric and electronic structural properties.Further analysis indicates the interactions between two superatoms are too weak to break the structure of monomers,which is confirmed by the first-principles molecular dynamics simulations.With these superatoms as the basic units,a series of robust one-dimensional and two-dimensional nanostructures are fabricated.Our findings provide a general strategy to take advantage of superatoms in regulating bonding compared to natural atoms,which paves the way for the bottom-up design of materials with collective properties.