Theoretical Study On The Electronic Property Regulation And Stability Mechanism Of Several Superatom Clusters

Clusters are multinucleate aggregates between atoms and macroscopic matter.The unique bridging role makes them an ideal model for linking macroscopic solids and microstructures,and plays an important role in interdisciplinary fields and the creation of a new class of nanomaterials.In recent years,the introduction of the concept of superatoms has made remarkable developments in the field of cluster science,making the design of materials surpass the concept of atomic structure.It is of great significance to explore the regulation of cluster electronic properties,design new superatomic clusters and cluster materials,and improve the cluster stability mechanism.Based on density functional theory,this paper uses ligand fields to directionally control the electronic properties of two types of superatoms,analyzes the geometry and electronic structure of these systems,and further explores the potential of these superatom clusters in the construction of cluster-assembled nanomaterials.Based on the abnormally stable 8e open-shell all-metal cluster system,a new cluster stability mechanism of "S-P molecular orbital coupling" is proposed.The main content of this article is as following:1.Seeking novel superatoms with tunable electronic and magnetic properties has attracted much interest due to their potential application in cluster assembly nanomaterials.By employing density functional theory(DFT)calculations,the recently observed superatomic WC cluster was adopted as the basic unit to construct larger polymeric clusters,namely(WC)n(n=2-7),and their structural evolution was explored to understand the growth pattern.An unusual odd-even pattern in structural evolution was disclosed.In addition,the regulation of the electronic properties of cubic W4C4 clusters by the CO(electron acceptor)and PH3(electron donor)ligands are discussed.Theoretical results show that the continuous attachment of CO and PH3 ligands causes the frontier orbital energy levels of the clusters to move directionally,which significantly enhances and reduces the adiabatic electron affinity(AEA)and adiabatic ionization potential(AIP)of the W4C4 clusters,respectively,leading to the formation of superhalogen and superalkali species with high magnetic moments.The observed ligand induced strategy highlighted here could be used as an effective way to tune the electronic and magnetic properties of clusters resulting in the formation of novel superatoms.In addition,the W4C4 cluster was assembled into a 3-D cubic honeycomb-shaped cluster material,and studied its electronic property,revealing its special metallic properties.In order to overcome the traditional limitation of changing the arrangement of electron shells to construct superatoms,we discussed the regulation of CNC6H4NC ligand on the electronic properties of aluminum-based superatomic XAl12(M=Al,C,P)clusters with different shell occupancy.Theoretical calculation results show that,different from the traditional electron shell regulation strategy,the ligand can significantly reduce the cluster ionization potential without changing the shell arrangement,and form superalkaline species.In addition,the ligand can effectively connect aluminum-based superatomic clusters to form stable superatomic molecules.These superatomic molecules have NLO(nonlinear optical)responses.The first hyperpolarizability(?0)of CAl12(CNC6H4NC)PAl12 is up to 5.22 × 106 a.u.under 0.012 a.u.OEEF(oriented external electric field),which can be used as a nonlinear optical material with excellent performance.Finally,we constructed 1D nanowire with the ligand aluminum-based superatomic cluster XAl12(CNC6H4NC)(M=Al,C,P),and explored its electronic structure and optical properties.The Huckel's rule,Baird's rule,and electronic shell closure model are classical and well-established concepts in chemistry,which have long been employed in rationalizing the aromaticity/antiaromaticity of organic species and stability of inorganic clusters.Therefore,it is extremely challenging to find new species of clusters with special stability out of the fundamental frameworks of these rules,and it is of great significance to perfect cluster stability models.Herein,we demonstrated via high-level theory,59 all-metal clusters possessed not only dual aromaticity in both the ground and excited states but also unexpectedly more stable open-shell geometries,unprecedentedly showing the limitation of the three fundamental rules simultaneously.Further,analogous to the concept of s-p hybridization in organic chemistry,we propose a new cluster stability mechanism of "S-P molecular orbital coupling".This discovery has certain guiding significance for a comprehensive understanding of the aromaticity and stability mechanism of inorganic metal clusters.