星际炔氰分子电子结构和分子振动的理论研究

Theoretical Studies of the Electronic Structure and Molecular Vibration on Interstellar Cyanopolylacetylenes

用MINDO/3法计算了星际炔氰分子(HC_(2)nCN,n=0,1,…,5)的电子结构和振动频率;得出了炔氰分子的HOMO、LUMO、电子总能量E_(T)与n之间的线性关系。炔氰分子n愈大,HOMO愈高,LUMO愈低,体系愈不稳定。由计算的振动频率和对振动模式的分析可知,在炔氰分子中(HCN除外),应有频率约为3820cm^(-1)的H—C伸缩振动和800cm^(-1)的H—C—C弯曲振动这样的特征振动。

The interstallar cyahopolyacetylenc(HC_(2)nCN,n=0,1...,5)have been studied theoretically by means of MINDO/3 method.The linear relationships between HOMO,LUMOand total electronic energies E_(T) with n in cyanopolyacetylenes are found.On the linear relationships of these frontier orbitals,the larger the n,the higher the HOMOs'and the lower the LUMOs'in cyanopolyacetylenes.In consequence,the system is more unstable.On the calculated vibrational frequencies and the analysis of the mode of vibration,the existence of some characteristic vibrations such as H-Cstretch vibration about 3820 cm^(-1) and H-C-Cbent vibration about 800 cm^(-1) is predicted for cyanopolyacetylenes except HCN.