Study On The Structures And Properties Of Rare Earth Metal(Dy,Tb)Doped Silicon Clusters

Semiconductor materials,especially silicon-based,they are not only as building blocks for developing novel and controllable nanomaterials,their undeniable importance but also in the modern microelectronics industry.Because of the presence of a lot of unsaturated dangling bonds of pure Si clusters lead to the Si cluster itself unsuitability as nanoscale building blocks.Rare earth?RE?is known as the industrial“gold”.Rare earth metal introducing Si clusters can not only stabilize the Si clusters,but also introduce new magnetic,optical,electrical and other properties.Rare earth metal doped silicon clusters are broad applicated in microelectronics industries,energy,materials and chemical industries.Through use the density functional theory study the ground state structures and structural evolution models of RMSi_n?RM=Dy,Tb,n?20?clusters and their anions.Their adiabatic electron affinity?AEA?,electron vertical dissociation energy?VDE?,atomization energy,and HOMO-LUMO energy gap have been calculated.Their photoelectron spectroscopy has been simulated.And their relative stabilities have been analysed.The equilibrium geometries,electronic structures and electronic properties including adiabatic electron affinity?AEA?,vertical detachment energy?VDE?,simulated photoelectron spectroscopy,HOMO-LUMO gap,charge transfer,and magnetic moment for Dy Si_n?n=3-10?clusters and their anions were systematically investigated by using the ABCluster global search technique combined with a B2PLYP double-hybrid density functional methods.The results showed that the?1?lowest energy structure of neutral Dy Si_n?n=3-10?can be regarded as substituting a Si atom of the ground state structure of Si_n+1with a Dy atom.For anions,the extra electron effect on the structure is significant.Starting from n=6,the lowest energy structures of Dy Si_n^??n=3-10?differ from those of neutral.?2?The ground state is quintuplet electronic state for Dy Si_n?n=3-10?excluding Dy Si₄and Dy Si₉,which is a septet electronic state.For anions,the ground state is a sextuplet electronic state.?3?Analyses of HOMO-LUMO gaps indicated that doping Dy atom to silicon clusters can improve significantly their photochemical reactivity,especially for Dy Si₉.?4?Analyses of NPA revealed that the 4f electrons of Dy in Dy Si₄,Dy Si₉,and Dy Si_n^??n=4,?participate in bonding.That is,Dy Si_nbelongs to the AB type.The 4f electrons of Dy atom provide substantially the total magnetic moments for Dy Si_nand their anions.?5?The dissociation energies of Ln?Ln=Pr,Sm,Eu,Gd,Ho,and Dy?from Ln Si_nand their anions were evaluated to examine the relative stabilities.The global minimal structures of terbium-doped Si clusters and their anions Tb Si_n^0/-?n=6-18?are confirmed by employing the ABCluster unbiased global search technique combined with a B2PLYP double-hybrid density functional and comparing consistency of simulated and experimental photoelectron spectroscopy?PES?.The results demonstrated that?1?structural evolution models for neutral clusters prefer Tb-substitutional to Tb-encapsulated configuration starting from n=16.While for the corresponding anionic clusters,the structural evolution models adopt Tb-linked structures to encapsulated motif.?2?The natural population analysis?NPA?revealed that the 4f electrons of Tb atom in Tb Si_n^0/-?n=6-18?clusters participate in bonding.The way to participate in bonding is one4f electron transition to 5d orbital?[Xe]6s²4f ⁹?[Xe]6s²4f ⁸5d¹?,which significantly affects the cluster's magnetism and appearance of PES.The total magnetic moments of neutral Tb Si_nand the corresponding anions maintain at 7?B and 6?B,respectively,which are larger than that of an isolated Tb atom.?3?The HOMO-LUMO energy gap,relative stability and chemical bonding analysis demonstrated that Tb Si₁₆^-cluster is a super atomic cluster with fine thermodynamic and moderate chemical stability.