The Study On The Structure And Property Of Praseodymium Doped Silicon Clusters With Density Functional Theory

Rare earth metal(REM)atoms doping inside silicon clusters can not only enhance the stability of the silicon cage,but also exhibit magnetism and other novel properties.Rare earth metal atom-doped silicon clusters can serve as the building blocks of new functional assembled materials and possess significant value in the field of design for novel materials.The objective of the present study is to systematically apply several carefully selected DFT methods to study on the structures and properties of praseodymium-doped silicon clusters PrSi_n(n=3–9)and their anions,and neutral PrSi_n(n=10–21)species.At the B3LYP,PBE0,and m PW2 PLYP levels,the equilibrium geometries and properties such as adiabatic electron affinities(AEAs),simulated photoelectron spectra(PES),dissociation energies,relative stabilities,HOMO–LUMO gaps,charges transfer,and magnetic moments of PrSi_n(n=3–9)and their anions have been made a detailed study combined with SEG/ECP basis set.The results indicate that the double-hybrid functional containing MP2 correlation functionals can accurately predict the ground state structure and property of Pr-doped Si clusters.The results are as follows:(1)starting from n=7,the ground state structures of PrSi_n(n=3–9)anions do not belong to “substitutional structure”.When binding an electron to the ground state structure of the neutral,the extra electron effect on the ground state structure is intense.The ground state structures for PrSi3-,PrSi6-,and PrSi8-are different from their neutral ones.(2)The average absolute deviations from experiment are only 0.05 eV,and the maximum deviations are 0.10 e V.(3)The accordance between the experimental PES and the theoretical simulations indicates that the ground state structures of PrSi_n–(n=4–9)are trustworthy.(4)The experimental PES of PrSi4-is reassigned in light of the theoretical results,and the experimental AEAs of 2.0±0.1 eV are obtained and not the 1.6±0.1 eV.(5)The DEs of Pr atom from PrSi_n species are calculated.(6)The HOMO–LUMO gaps results show that doping Pr atom to Si_n(n=3–9)clusters raises the photochemical sensitivity.But the effect of raising photochemical sensitivity is not as good as the effect of the doping Eu or Sm to silicon species.(7)A large proportion of the total magnetic moments for all of these species are contributed by Pr atom.(8)The natural population analysis indicates that the 4f electron of Pr atoms participates in bonding,but the magnetic moments are not quenched,a large proportion of the total magnetic moments for PrSi_n species(except for PrSi3–)are contributed by Pr atom.At the B3LYP and PBE0 levels,the structures and properties of the neutral PrSi_n(n=10–21)species considering various spin configurations were systematically studied using PBE0 and B3 LYP schemes in combination with SEG/ECP basis set.The results reveal that(1)the ground-state structures of PrSi_n(n=10–21)obtained by the cc-pVDZ and the cc-pVTZ basis set are the same.(2)Starting from n=20,the ground-state structures of PrSi_n are evaluated to be endohedral cagelike clusters that the PrSi20 is the smallest cagelike ground state structure of PrSi_n species.(3)Analyses of stabilities indicate that the PrSi11,PrSi13,PrSi16 and PrSi20 are more stable than the others,especially the PrSi20.(4)Analyses of HOMO–LUMO gaps show that introducing Pr into Si_n(n=10–21)elevates the photochemical sensitivity,especially for PrSi20.(5)Calculated result of magnetic moment and charge transfer shows that the 4f electrons of Pr in the clusters are changed,especially in endohedral structures such as PrSi20,in which one electron transfers from 4f to 5d orbital.A large proportion of the total magnetic moments for PrSi_n species are contributed by Pr atom,and the magnetic moments are not quenched when the cagelike structures form.The largest charge transfer for endohedral structure reveals that the bonding between Pr and Si_n is ionic in nature and very strong and the PrSi20 is the most stable among all of these clusters.