Theory Study On Structures And Properties Of Rare-earth Metal(Er)Doped Silicon Clusters

Silicon-based clusters,as one of the most significant materials in modern industry,have great concern among the worldwide.Doping rare earth metal into silicon-based cluster can evidently improve their stabilities,photosensitiveness and magnetic of pure silicon-based clusters which lacking stabilities.The silicon-based clusters doped rare earth metal with new properties can be used as building units of novel self-assembled materials and design functional materials.The lowest energy structures of ErSi_n?n=3–10?and their anions,optimized from the initial geometries chose using the ABCluster global search technique,are probed using the large basis sets combined at the PBEPBE,TPSSh and B3LYP schemes,and the large basis sets are augmented to studying electron affinities,dissociation energies,HOMO-LUMO gaps,charge population as well as magnetic moments,and simulated photoelectron spectra.The details are as follows:?1?The result of the obtained lowest energy structures of ErSi_n?n=3–10?indicate that the growth patterns of ErSi_n can be regarded as substituting a Si atom of pure Si_n clusters with a Er atom,in which the lowest energy structures of ErSi_n^-is different from the corresponding neutral lowest energy structures from n=7.The results revealed that the ground state is triplet electronic state for ErSi_n?n=3–10?excluded ErSi₄,for which the triplet and quintuplet state compete with each other.For anion ErSi_n^-?n=3–10?,the spin multiplicity is quartet state.?2?The dissociation energy values of ErSi₅,ErSi₈,ErSi₅^-and ErSi₉^-show that they are more stable.?3?HOMO-LUMO gaps predict that the photochemical activity of ErSi_n?n=3-10?clusters,except n=3,is stronger than that of pure Si_n clusters.Furthermore,ErSi₄,ErSi₆ and ErSi₉ have relatively better photosensitivity.?4?The NPA shows that the total magnetic moments of ErSi_n and their anions are mainly provided by the 4f electrons of Er atom.?5?The AEAs,VDEs and simulated PES of ErSi_n?n=3–10?are reported.Using two hybrid density functional methods?TPSSh and B3LYP?obtain the lowest energy structures of the ErSi_n?n=11-21?cluster by combining the large basis set,besides the binding energies,HOMO-LUMO gaps,charge population and magnetic moments of clusters.The details of studying ErSi_n?n=11-21?clusters are as follows:?1?The lowest energy structures of ErSi_n cluster from n=10 to n=17 are verified to be substituting a Si atom of pure Si_n clusters with a Er atom at TPSSh method,while beginning from n=18they are more inclined to come into being cage configuration in which Er surround with Si_n.However,the lowest energy structures come into being the cage configuration from n=16at the B3LYP method.?2?Considering the binding energy,second-order energy difference and dissociation energy calculated by the two methods,ErSi₁₈ and ErSi₂₀ are more stable than those of other clusters.?3?The HOMO-LUMO gaps show that clusters doped Er atoms can greatly improve their photosensitivity.Among them,the gap of ErSi₂₀ is very low,which are more likely to occur the photochemical reaction than other ErSi_n clusters.?4?Analyzing NPA of Er atom in ErSi_n cluster,the total magnetic moments of the ErSi_n?n=11-21?cluster are mainly provided by Er atom,and the magnetic moments of the cluster are strengthened followed the formation of the cage configuration.