C40异构体的结构和稳定性的理论研究

利用Gaussian98程序,采用密度泛函(DFT)方法中的B3LYP,选用6-31G基组对富勒烯(Fullerene)C40的6种异构体[D5d,Td,D2h,C3v,D2(Ⅰ),D2(Ⅱ)]进行了几何构型优化,其中,对于Td对称性的C40由于易发生Jahn-Teller畸变,则降低其对称性为D2d,再进行优化.对它们的平衡几何和电子结构进行了比较具体的分析,同时,根据计算得到的总能量推断出这6种异构体的稳定性顺序是D2(Ⅰ)>D5d>Td>C3v>D2h>D2(Ⅱ).

Theoretical Studies on the Structures and Stability of C40 Isomers

The Becke-3-Lee-Yang-Parr(B3LYP) method and 6-31G basis set was employed to study the equilibrium geometries and electronic structures of six kinds of C40 fullerene isomers, i.e., the isomers with D5d, Td, D2h, C3v, D2(Ⅰ) and D2(Ⅱ) symmetries. Due to the Jahn-Teller distortion we calculated the D2d(Td) structure in stead of Td strucure of C40. Mealwhile, the stability order of the six kinds of C40 isomers was judged from the total energies of them.According to our calculations, the stability order is D2(Ⅰ)>D5d>D2d(Td)>C3v>D2h>D2(Ⅱ), which is in good agreement with Salcedo et al.′s computational result of D5d>D2d>D2h at the HF/3-21G level, and is consistent with Zhang et al.′s proposal that the D2(Ⅰ) structure of C40 isomers is the most stable one. In addition, our calculated results also confirmed that the HOMo-LUMO gap is not reliable to predict the stability of fullerenes.