使用SIESTA搭配B3LYP的方法來研究矽團簇取代基效應對其光學特性造成的影響，取代的方式是全取代。對於Td點群的矽團簇，選擇Si35X36來進行計算。選用的取代基有H、CH3、C2H5、C3H7、C2H3、OH、OCH3、NH2、CH2NH2、CN、SH、C3H6SH、C60，來計算取代後矽團簇的HOMO、LUMO與能隙值。計算結果得到烷基類取代矽團簇時能隙的大小相似，且均比氧化物、氮化物與硫化物取代能隙來的高。烷基類對能隙的影響力很小，且一般拉電子基取代會造成矽團簇的能隙產生紅位移的現象。對於Ih點群的矽團簇，則針對Si20X20進行計算，最後得到的結果與Td點群的矽團簇相似。 For the investigation of the optical properties of Si nanoclusters as a function of surface passivation, we carried out a B3LYP/SIESTA calculation in the Si35 core clusters with full passivated. For the Td symmetry,we calculated Si35X36.We predict the effect that different full alkyl-,C2H3- , OH-, NH2-, CH2NH2-, OCH3-, SH-, C3H6SH- ,C60 and CN-terminations have on the calculated HOMO, LUMO and energy gap. The calculated optical properties alkyl passivation Si35 nanoclusters [Si35(CH3)36, Si35(C2H5)36 and Si35(C3H7)36] are closed to one another, and are higher than those of oxide, nitride and sulfide passivations Si35 clusters. Concludly, the alkyl passivant weakly affect the optical gaps and the electron-withdrawing passivants generate the red-shifted for the energy gap of silicon nanoclusters.
