Theoretical Study On The Assembled Structures Of Superatomic Anion Al₆O^2- And The Electronic Structure Of Superalkali NM₄ Cluster

Cluster is a new level between atoms,molecules and macroscopic objects.Due to the special physical,chemical,and magnetic properties,cluster research is one of the current research hotspots.Some magic number clusters can mimic the chemical behavior of an atom in the periodic table and are called superatoms.Its main branches are superhalogen and superalkali,and they can be used as building units to synthesize new materials.This kind of material formed using superatomic clusters as building blocks by the way of“bottom up”is called cluster assemble material.The research of cluster assemble materials pushes the common materials with atom or molecule as basic units to a new level,and has greatly improved the practical use of clusters.In this paper,the main research contents are as follows.The structures of Al₆OK₂ are determined using unbiased genetic algorithm combined with ab initio methods.It was experimentally confirmed that Al₇C^-possesses exceptional stability.This study offers the interpretation for the hetero magic clusters.The delocalized Jellium orbitals of the metal moieties and the atomic orbitals of the nonmetal atom interact strongly and form bonding and antibonding orbitals.The orbital interactions lead to closed s²p⁶shells of the nonmetal atom and the 18-electron S²P⁶D¹⁰shells of the metal moieties.The 26 valence electrons correspond to a strong magic number.Al₆OK₂ cluster is formed by ionically bonding two K⁺cations to the Al₆O^2-anion.The electronic structures of Al₆O^2-core also accord with the Wade-Mingos rule.We build two typical ionic AB₂ crystals.The interactions between the building units reach 1.48 eV.The Al₆OK₂ assembled crystals are wide gap semiconductors.The phonon dispersion curves and elastic constants confirm the assembled structures are dynamically stable.The lowest energy isomers of superalkali NM₄ clusters with homo-and hetero-alkalis M=Li,Na,K are determined using USPEX and G3 method.Their vertical ionization potentials?3.22³.74 eV?are lower than that of Cs atom.The stabilities of the superalkalis are guaranteed by the binding energies and positive energies of the dissociation channel NM₃+M',and NLi₄ is the most stable among the NM₄ clusters.The high stability and tetrahedral geometry make these species idea units for building new materials.