Theoretical Investigation On Geometrical And Electronic Structure Of The RhSi_n(n=1-6) Clusters

The transition metal silicon clusters have attracted attention , both theoretically and experimentally ,because the transition metal doped silicon clusters are a group of semiconducting cluster with great importance for applications in microelecronic technology and new material design research . Structural and electronic properties of the neutral RhSin (n=l-6) clusters , charged RhSin+ clusters and RhSin- (n=l-6)clusters are investigated computationally by density functional method.The possible geometries of the RhSin(n=l-6) clusters with various spin value are optimized by using density functional method at the B3LYP/LanL2DZ level . The ground state structures of the RhSin(n=l-6) clusters are obtained . The averaged binding energy , fragmentation energy , natural population , HOMO-LUMO gap as well as magnetism are discussed . Theoretical results show that the most stable RhSin(n=l-6) isomers keep the same frameworks as the corresponding Sin+1 clusters only with a slight distortion in geometry . Meanwhile , natural populations indicate that charges are transferred mainly from the Si atoms to the Rh atom in the lowest-energy RhSin(n=l-6) . In addition , the investigations on the atomic averaged binding energies and fragmentation energies exhibit that the RhSi3 is the most stable structure relatively . Furthermore , the analysis of magnetism shows that the magnetic moment in the RhSin(n=l-6) arises from primarily by 4d orbitals of Rh atom . Finally , the HOMO-LUMO gap is discussed that RhSi3 is more stable than the others RhSin clusters , which is in good agreement with the result of fragmentation energies.In order to compare with the experiment result , structural and electronic properties of RhSin+ clusters and RhSin- (n=l-6)clusters are also studied systematically using density functional method at the B3LYP/LanL2DZ level, most of the RhSin+ and RhSin- structures keep basically similar frameworks as the corresponding neutral RhSin clusters, serious deformations happen to RhSi4~+ and RhSi2- clusters, which is well agreed with the differences between the calculated vertical ionization potentials and adiabatic ionization potentials, vertical affinicitiespotentials and adiabatic affinicities potentials. At the same time, the atomic averaged binding energies of most RhSin+ and RhSin" clusters universally increase(except for RhSi3+ cluster), which suggest the stabilities of RhSin+ and RhSin" clusters have been improved.The feature of RhSi3+and RhSi3~ clusters are more stable than other RhSin+ and RhSin" structures. HOMO-LUMO gap of RhSin+ clusters universally increase, but RhSin" clusters decrease. At last ,the excited state of RhSin+ and RhSin" clusters are analysed elementarily, which indicate that excitation spectra of RhSin+ and RhSin+ clusters is visible light.