本文采用 MNDO 方法研究了 Si_n, Si_n⁺ 和 Si_n²⁺ (n=2-6) 簇的原子结构，得到了一系列稳定的簇结构，并确定出每一类簇所对应的最佳稳定结构．从中发现，无论 Si_n, Si_n⁺ 还是 Si_n²⁺ 簇，都存在共同的“幻数’，即 4, 5, 6, 然而, Si_n, Si_n⁺ 和 Si_n²⁺ 对应的稳定结构一般是各不相同的．本文的结构说明，以往人们单纯从中性 Si_n 簇的研究去推断并解释 Si_n 离子族的结构和性质是不恰当的，荷电将改变原子簇的构型．文中还指出了几个以前没有发现的稳定构型．

The atomic structures of Si_n, Si_n⁺ and Si_n²⁺ (n=2-6) have been studied by using MNDO method. A series of equilibrium structures have been obtained, the most stable ones are determined. Si_n, Si_n⁺ and Si_n²⁺ have the common magic numbers which are 4, 5 and 6, but the corresponding equilibrium structures are different. The results suggest that it is unreasonable to deduce the structures of ionic silicon clusters from those of neutral silicon clusters and that charging can change the structures of atomic clusters. Moreover, several new equilibrium structures are also given.