Study On Structure And Properties Of Rare Earth Metal Ce Doped Silicon Clusters CeSi_n(n=4-20)

Rare earth metal-doped silicon clusters not only improve the photochemical reactivity and thermodynamic stability of the clusters,but also have special optical and magnetic properties,and can be widely used in materials,microelectronics,environment and other fields.By changing the shape and size of rare earth metal-doped silicon clusters,it can become the basic unit of new materials,which is of great significance for the design of new materials for different purposes.In this paper,the density functional theory method is used to systematically study the ground state structure and physical and chemical properties of rare earth metal Ce-doped silicon neutral cluster CeSi_n?n=4-20?and anionic cluster CeSi_n^-?n=4-20?.For CeSi_n?n=4-20?neutral clusters,the double-hybrid density functional?m PW2PLYP?method is used in combination with the aug-cc-p VTZ/ECP basis set to systematically study the ground state structure and properties.The results show that:?1?For the ground state structure of CeSi_n?n=4-20?neutral clusters,when n?17,the ground state structure of CeSi_n?n=4-20?is Ce atom substituted for a Si atom in the most stable structure of Si_n+1clusters;when n=17-19,the ground state structure is a Ce-linked structure where cerium atoms connect two small silicon clusters;when n?20,the ground state structure is a cerium atom wrapped Cage structure in silicon cage clusters.?2?Atomization energy and second energy difference shows that doping cerium atoms into pure silicon clusters can improve the stability of the clusters,and CeSi₂₀clusters are the most stable clusters among neutral clusters.?3?The HOMO-LUMO energy gap results show that CeSi_n?n=4-20?neutral clusters have higher photochemical reactivity than pure silicon clusters,and the neutral cluster CeSi₂₀clusters have the best photochemical reactivity.?4?The results of charge transfer analysis show that the 4f electrons of cerium atoms in the doped clusters have not changed and do not participate in the bonding.?5?Magnetic analysis showed that the magnetism of CeSi_nneutral clusters did not disappear,and the total magnetic moment was 2?B.Among the valence electrons 4f provided the most magnetic moment,almost half of the total magnetic moment.For CeSi_n^-?n=4-20?anionic clusters,the double-hybrid density functional method was used to study the ground state structure and spectrum,relative stability,physical and chemical reactivity and magnetic properties.The research results show that:?1?When n=4-7,the ground state structure of CeSi_n^-?n=4-20?clustes is a substituted structure;when n=8-18?except CeSi₉^-?,the ground state structure is Ce-linked structure;when n=19-20,the ground state structure is a cage structure;the influence of extra electrons makes the ground state configuration of anionic clusters and neutral clusters have a clear gap.?2?Predict the adiabatic electron affinity?AEA?and vertical electron dissociation energy?VDE?of CeSi_n^-?n=4-20?clusters,and simulate CeSi_n^-?n=4-20?photoelectron spectrum of anionic clusters.?3?Relative stability analysis shows that anionic clusters are more stable than neutral clusters,and CeSi₂₀^-is the most stable cluster among anionic clusters.?4?HOMO-LUMO energy gap analysis shows that extra electrons affect the optical reactivity of the cluster.?5?Charge transfer and magnetic moment analysis show that the 4f electrons of cerium atoms in the anion cluster do not participate in the bonding and retain the magnetism,providing the total magnetic moment 2?B for the cluster.?6?The chemical bond analysis results show that CeSi₂₀^-is a super atom,and the valence electron shell is arranged as 1S²1P⁶1D¹⁰1F¹⁴1G⁸2S²1G¹⁰2P⁶2D¹⁰3S²2F¹⁴.CeSi^-₂₀not only has high thermodynamic stability,but also strong photochemical reactivity,it can become the most suitable basic unit for constructing new multi-functional environment-friendly materials.