扶手椅形单壁碳纳米管环氧异构体的理论研究

用半经验AM1方法对不同直径的单壁碳纳米管(3,3)/C₄₂H₁₂,(4,4)/C₅₆H₁₆,(5,5)/C₇₀H₂₀和(6,6)/C₈₄H₂₄本体及其环氧衍生物进行了理论研究.结果表明,对于直径较大的(5,5)C₇₀H₂₀和(6,6)/C₈₄H₂₄单壁碳纳米管,可以得到4种不同的环氧化异构体.而直径较小的单壁碳纳米管(3,3)/C₄₂H₁₂和(4,4)/C₅₆H₁₆,只能得到3种异构体.讨论了这些异构体的生成热(H_f)、离子势、电子亲和能、最低非占据轨道和最高占据轨道的能级差E_g等参数及其与单壁碳纳米管直径的关系,并排列了这些异构体的稳定性次序.同时,用POAV程序分析了单壁碳纳米管中sp²碳原子轨道的再次杂化和张力的大小.

Theoretical Investigation of Cyclooxide Isomers of Armchair Single-walled Carbon Nanotubes

The geometries of Armchair single walled carbon nanotubes with different lengths and diameters, i.e . (3,3)/C 42 H 12 , (4,4)/C 56 H 16 , (5,5)/C 70 H 20 and (6,6)/C 84 H 24 were optimized by Gaussian 94 programme, and so did their cyclooxide isomers. The results showed that there were four isomers found for shorter and enlarged carbon nanotubes, which were named as Sloppy closed(S closed), Sloppy open(S open), Horizontal closed(H closed) and Horizontal open(H open) isomers; and there were only three of them (without H closed isomer) were found for longer and slimmer carbon nanotubes. After frequency analysis, there were no negative frequencies found for them, which indicated that these isomers were all stable ones. At the same time, we investigated the heat of formation( H f), ionization potentials, distort energies, electron affinities energies and the energy gap of HOMO LUMO of these carbon nanotubes and their corresponding cyclooxide isomers, and also discussed the relationship between the stability and these parameters. In addition, we explored sp 2 rehybridization of carbon atoms and strain force of these nanotubes using POAV programme.