Study On The Structures And Properties Of Transition Metal Doped Silicon And Germanium Clusters TMX_n (TM=Cu,Ag,Au;X=Si,Ge) With Double Hybrid Density Functional Method

With the development of nanotechnology,clusters have become the research hotspot in many scientific fields.Transition metal doped semiconductor clusters have been attracting much attention due to their unique physical and chemical properties.Theoretical researches on the stable structures and electronic properties of transition metal doped semiconductor clusters can provide necessary theoretical guidance for further experimental researches and practical applications.In this paper,artificial bee colony algorithm for cluster(ABCluster)combined with double hybrid density functional method is used to study the ground state structure and evolution patterns of neutral,anionic and cationic clusters TMX_n(TM=Cu,Ag,Au,X=Si,Ge;n=1-13).The adiabatic electron affinity(AEA),vertical detachment energy(VDE),ionization potential(IP),binding energy per atom(E_b)and HOMO-LUMO energy gap of the ground state structure have been calculated.Their photoelectron energy spectrums(PES)have been simulated.And their natural population analysis(NPA)has been performed.At the mPW2PLYP/aug-cc-pVTZ//mPW2PLY/cc-pVTZ level of theory,the structures and electronic properties of CuSi_n^0/-/+and CuGe_n⁺(n=1-13)clusters have been investigated The results indicated that:(i)The evolution patterns of the CuSi_n^0/-/+(n=1-13)clusters are substituted configurations for neutral and anionic clusters when n?11,but attaching configurations for cationic clusters when n?11.Moreover the smallest size of encapsulated configuration is formed when n=12.The evolution pattern of the CuGe_n⁺(n=1-13)clusters are from attaching configurations to encapsulated configuration starting from n=9.(ii)The E_bof CuSi_n^0/-/+clusters is lower than that of pure Si_n+1^0/-/+clusters.It is to say that introducing Cuatom to pure Si_n+1^0/-/+clusters decrease the stabilities of pure clusters.And after addition of Cuatom into pure Ge⁺_n+1(n=1-8)clusters,the E_bof CuGe_n⁺(n=1-8)clusters becomes lower than the E_bof pure clusters.On contrary,the E_bof CuGe_n⁺for n=9-13,especially those which are encapsulated configuration,is higher than the E_bof pure Ge⁺_n+1(n=9-13)clusters.(iii)Ionization potential revealed that it is reduced after introducing Cuatom to pure Si_nand Ge_nclusters.(iv)The result of NPA demonstrated that copper atom in clusters acts as electron acceptor after forming the encapsulated configuration.(v)CuGe⁺₁₀,satisfying the superatomic electronic configurations,has not only good thermodynamic stability,but also relatively good chemical stability,making it the most suitable building block for multi-functional nanomaterials.At the mPW2PLYP/aug-cc-pVTZ(Si,Ge),aug-cc-pVTZ-PP(Ag)//mPW2PLY/cc-pVTZ(Ge),cc-pVTZ-PP(Ge,Ag)level of theory,the structures and electronic properties of AgSi_n^0/-/+and AgGe_n^0/-/+(n=1-13)clusters have been investigated.The results revealed that:(i)The ground state structure of AgSi_n^0/-/+(n=1-13)and AgGe_n^0/-/+(n=1-11)clusters are attaching configurations.For neutral and anionic clusters,they are encapsulated configurations from n=12,but n=13 for cationic cluster.(ii)The E_bof AgSi_n^0/-/+and AgGe_n^0/-/+(n=1-13)clusters are lower than the E_bof pure Si_n+1^0/-/+and Ge_n+1^0/-/+clusters,respectively.This indicated that introducing Agatom to both pure Si_n+1^0/-/+and Ge_n+1^0/-/+clusters decrease their stabilities.(iii)It is observed that ionization potential is reduced after introducing Agatom to pure Si_nand Ge_nclusters.(iv)Analysis of NPA revealed that the 4d electrons of Agatom in AgSi_n^0/-/+and AgGe_n^0/-/+(n=1-13)clusters hardly participate in bonding.Furthermore,Agatom mainly acts as electron acceptor in encapsulated clusters.At the mPW2PLYP/aug-cc-pVTZ(Si,Ge),aug-cc-pVTZ-PP(Au)//mPW2PLY/cc-pVTZ(Ge),cc-pVTZ-PP(Ge,Au)level of theory,the structures and electronic properties of AuSi_n^0/-/+and AuGe_n^0/-/+(n=1-13)clusters have been investigated.The results indicated that:(i)The ground state structure of AuSi_n^0/-/+(n=1-13)and AuGe_n^0/-/+(n=1-10)clusters are attaching configurations.For neutral and cationic clusters,the ground state structure are encapsulated configurations for n=11-13.For the anionic cluster,it is encapsulated configuration when n=12.(ii)When n=3-13,the E_bof AuSi_n^0/-/+and AuGe_n^0/-/+clusters is lower than the E_bof pure Si_n+1^0/-/+and Ge_n+1^0/-/+clusters,respectively,indicating that doping Auatom to both pure clusters decrease the stabilities.(iii)Observations exhibited the fact that ionization potential is reduced after doping Auatom to pure Si_nand Ge_nclusters.(iv)Compared with Cuand Agatom-doped silicon clusters:AuSi_nclusters have the best thermodynamic stability.Compared with Cuand Agatom-doped germanium clusters:when n=1-8,the AuGe_nclusters has the best thermodynamic stability;when n?9,the CuGe_nclusters has the best thermodynamic stability.