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

Rare earth metal atom-doped silicon clusters may not only stabilize silicon clusters but also make them serving as the building blocks of new functional assembled materials with new properties(magnetic,optical,charges transfer and catalytic,etc.),hence,it possesses significant value in the field of design for novel materials.The study on the structure and properties of the clusters HoSi_n(n=3-20)have been systematically investigated using different density functional methods.The clusters HoSi_n(n=3-9)and their anions have been examined by means of four density functional theory(DFT)methods(B3LYP,PBE,PBE0 and mPW2PLYP)in combination with the cc-pVTZ basis set and relativistic small-core Stuttgart effective core potentials(ECP28MWB).The results showed that:(1)The double-hybrid functional containing part of the MP2 correlation functionals can accurately predict the ground state structure and property of Ho-doped Si clusters.The ground state structure for neutral HoSi_n is predicted to be sextuplet electronic sate.The ground state geometries for HoSi_n(n=3-9)excluded HoSi7 are substitutional structure.(2)The ground state structure of HoSi_n? is evaluated to be quintuplet electronic state.The AEAs predicted by mPW2 PLYP method is in excellent agreement with the experimental values.The mean absolute error for theoretical AEAs of HoSi_n(n=4-9)is only 0.04 eV,and the maximum error is 0.09 eV.The simulated PES for HoSi_n?(n=5-9)is in agreement with the experimental PES.(3)The DEs of Ho atom from HoSi_n species has the local minimum at n=4 and7,and the maximum value at n=5 and 8.(4)The HOMO-LUMO gap analysis indicates that doping rare-metal atom can obviously raise the photochemical reactivity of Si clusters.(5)The NPA shows that the magnetic moments of HoSi_n(n=3-9)and their anions are mainly contributed by Ho atom,and the magnetic moments are not quenched when the cagelike structures form.The clusters HoSi_n(n=10-20)have been examined theoretically using the B3 LYP and PBE0 functionals in combination with the cc-p VDZ basis set and relativistic small-core Stuttgart effective core potentials(ECP28MWB).The results were obtained:(1)When n=12-15,the most stable structures of the HoSi_n clusters are predicted to have exohedral geometries and a quartet ground state.However,the most stable structures were found to be endohedral frameworks with a sextuplet ground state when n=16-20.And the HoSi16 is the smallest cagelike ground state structure of PrSin species.(2)In light of the results for cluster relative stabilities,HoSi13,HoSi16,HoSi18,and HoSi20 were calculated to be more stable than the other clusters.(3)In light of the results for cluster hardness,doping Ho into the other Sin clusters increases their photochemical sensitivity,especially the HoSi20.(4)Analyses of the intracluster charge transfer revealed that there is charge transfer from the Ho atom to the Sin cluster when HoSi_n(n=12-15)clusters with exohedral structures are created.However,charge transfer occurs in the opposite direction when HoSi_n(n=16-20)clusters with endohedral structures are created.This shows that Ho acts as an electron acceptor when the Ho atom is encapsulated in the Sin cage.(5)Magnetic moment analysis of the clusters showed that a large proportion of the total magnetic moments for HoSi_n species are contributed by Ho atom,and the magnetic moments are not quenched when the cagelike structures form.A 4f electron does participate in the bonding within the most stable endohedral frameworks of the HoSi_n(n=16-20)clusters;in these structures.Also,the total magnetic moments of the HoSi_n(n=16-20)clusters are incredible.(6)Due to its especially high chemical stability and relative stability,the endohedral HoSi16 cluster is particularly well suited for use as a building block in novel high-density magnetic storage nanomaterials.On the other hand,due to its prominent relative stability and photochemical sensitivity,the HoSi20 cluster(in which Ho is completely encapsulated)appears to be a highly suitable building block for novel optical and optoelectronic photosensitive nanomaterials.