Theoretical Studies On Charge Distribution And Skin Behavior Of Coinage Metal Superatoms

Clusters are complex systems constructed by multiple atoms.Their properties are not only dependent on the atomic properties in clusters,but also result from the interaction of the size,the structure and the constituent atoms.Because of the complexity in general clusters,it is difficult to understand clusters from the perspective of electronic structure and even regulate clusters,which further affects the application of clusters represented by basic properties such as optical,electrical and magnetic.With the deepening of understanding the basic physical laws in clusters,the concept of superatoms was proposed.The study in the highly symmetric structure and the atom-like electronic structure property of the superatoms has brought a broad prospect for the basic and applied research in clusters.In this work,the electronic structure properties of metallic superatoms have been investigated by first-principle density functional theory(DFT),especially the relationship between the charge distribution and the electron orbital occupation,and the relationship between the electronic structure and the bonding properties within superatoms.First,we studied the relationship between the charge distribution of clusters and the electron occupancy in the form of superatoms,and found the charge skin effect in the microscopic system.We report the neutral gold superatoms Au_n(n=13,55 and 147)and their anion structures[Au_n]^-.Results show that there are negative charges of-0.1e,-0.54 e and-1.16 e in the surface area corresponding neutral Au_n structures and they are mainly distributed in the 1D⁵ superatomic molecular orbitals(SAMOs)of Au₁₃,1F¹²1G¹⁵ SAMOs of Au₅₅,and 2D⁶ 1H²² 2F¹⁴ 1I⁶ 3S² 1J⁶ 1I⁸ 1J⁴ 3P¹ SAMOs of Au₁₄₇.Besides,adding an electron to the Au_n will bring much more surface negative charges of-1.08 e,-1.55 e and-2.14 e,which are mainly distributed in the 1D SAMO of[Au₁₃]^-,1G SAMO of[Au₅₅]^-and 3P SAMO of[Au₁₄₇]^-.All these show that there exists skin behavior of charge distribution in gold superatoms.Moreover,it is quite interesting that the added electron will cause the SAMOs rearrangement,especially in[Au₁₃]^-and[Au₅₅]^-,which will enhance the geometric symmetry of superatoms.Our work provides a new perspective on microelectronic structure in understanding the skin effects.This is of great significance design and synthesis of coinage metal superatoms to realize their high efficiency catalysis,adjustable magnetic properties and electron transport properties in the future.For actinide embedded metal superatoms with high angular momentum electrons,the difference in the composition and structure of different superatoms also leads to the difference in the internal charge distribution.By quantifying the contribution of induced interaction(that is orbital interaction)and electrostatic interaction to bonding,we can gain insight into the bonding properties in the systems.By quantifying the contribution of intramolecular orbital interaction and electrostatic interaction to bonding,the covalent and ionic properties of the systems can be further understood.The intramolecular interactions of the isoelectronic superatoms An@Au₆([Ac@Au]^-,Th@Au₆ and[Pa@Au₆]⁺)have been investigated by qualitative and quantitative analysis respectively.On the one hand,as the atomic numbers of actinides(Ac,Th,and Pa)increase,the electron density distribution of SAMOs tends to the central atoms,especially in 1S SAMOs,while 1P and 1D SAMOs have similar electron density distribution of SAMOs.On the other hand,although the bonding properties of isoelectronic superatoms An@Au₆ are similar and have the same SAMOs arrangement,when the actinide atoms(Ac,Th,and Pa)are embedded in Au₆,the different energies of the 5f orbitals will still make their bonding properties differ quantitatively.This may be one of the reasons for the change of the proportion in the covalent interaction and ion interaction.These results not only provide more quantitative references for studying the effect of active valence electron on the bonding properties of the equivalent electron superatoms,but also broaden the inspiration for exploring the properties and functional design of the coinage metal superatoms at the atomic level.In summary,we investigate the charge distribution in metallic superatoms and the effect of embedded actinide atoms on the intramolecular bonding properties of superatoms in this work.A clear relationship between the charge distribution and the electron orbital occupation in the superatom is found,and the skin behavior of the charge distribution in the superatom is explained from the perspective of the electronic structure.By analyzing the electronic structures of the high angular momentum superatoms formed by actinides embedded gold clusters,it is further found that the electron occupation pattern is closely related to the intramolecular bonding properties.This work provides an important reference value for the study of the electronic structure-based superatoms,and promotes the progress of science and technology in the design of superatomic devices based on metals.