摘要
用INDO系列方法对C78n(D3、D3h、D?h)进行系统研究,表明C78(D3)比C78(D3h、D?h)稳定,与理论计算及实验结果一致;且随n绝对值增大,C78n总能量升高;C78n(D3、D3h、D?h)异构体的部分离子发生了Jahn-Teller畸变.以优化构型为基础,用INDO/SCI方法首次计算了C78n的电子光谱,对电子跃迁进行理论指认,讨论C78n光谱的特征吸收与C78相比发生红移的原因.
The singlet of ions for C78n (D3, D3h and D?h) was studied by the INDO method. The D3 isomer of C78 is more stable than D3h and D?h, which is in agreement with theoretical and experimental results. The total energy of C78 is raised with the increasing of electric charge numbers, and Jahn-Teller distortion appers in some ions with D3, D3h and D?h symmetry. Based on the optimized geometries, electronic spectra of C78n were calculated by using INDO/SCI models for the first time. The UV bands of C78n will be red-shifted compared with those of C78 because of their narrower LUMO-HOMO energy gaps. The electronic transition was assigned theoretically and the reason of the red-shift of UV peaks for C78n was rationalized.
