乙炔—甲基乙炔共聚体及其掺杂体的能带结构研究  

Study on Band Structures of Acetylene-Methylacetylene Copolymers

作　　者：曹阳[1] 陈波[1] 

机构地区：[1]苏州大学化学系,苏州215006

出　　处：《Chinese Journal of Chemical Physics》1993年第2期167-171,共5页化学物理学报（英文）

摘　　要：本文用LCAO-SCF ab initio晶体轨道方法计算了乙炔—甲基乙炔共聚体的能带结构和碳链上的电荷分布情况,所选计算体系包括不同乙炔含量的共聚体及不同的锂掺杂浓度,文章主要讨论了甲基及锂掺杂对能带结构和碳链上电荷分布的影响以及乙炔—甲基乙炔共聚体掺杂后导电性提高的原因,并与聚乙炔及掺杂体系的结果进行了比较,解释了实验结果。The band structures of copolymers of acetylene and methylacetylene and their Li-doped systems are calculated by using LCAO-SCF ab initio crystal orbital method. The conduction band and valence band structures and energy gaps as well as the charge distribution in carbon-chain are studied to discuss the change of conducting properties of copolymers after doping. The influences of methyl group on the conducting properties are also discussed. Both different acetylene concentration in copolymers and different dopant concentration are taken into account. The calculated systems are (C_7H_8)_x, (C_8H_(10))_x, (C_7H_8Li)_x, (C_8H_(10)Li)_x, (C_7H_8Li_2)_x, and (C_8H_(10)Li_2)_x. The calculated results are compared with those of polyacetylene(CH)_x. On one hand, methyl(-CH_3) is a donor that charged a little, the π-electrons interact with π-orbitals in one-dimensional carbon chain through Baker-Nathan effect, which lowers conjugation affect in carbon chain and causes lowering of the energy gap. The conductivities of copolymers are therefore larger than those of polyacetylene; After doping with lithium, the charge in carbon chain partly disperses to methyl, so methyl group weakens the affect of dopant and the energy gap rises. The conductivities of doped copolymers are therefore smaller than those of doped polyacetylene on the other hand.

关 键 词：乙炔 甲基乙炔 共聚物 锂 能带结构 

分 类 号：O632.17[理学—高分子化学]