掺杂聚乙炔的能带结构计算  

Calculation of Band Structure of Doped Polyacetylene

作　　者：曹阳[1] 王友良[1] 陈波[1] 

机构地区：[1]苏州大学化学系

出　　处：《Chinese Journal of Chemical Physics》1989年第5期384-388,共5页化学物理学报（英文）

摘　　要：本文采用LCAO-SCF ab initio晶体轨道方法计算了聚乙炔和锂掺杂聚乙炔的导带和价带的能带结构,讨论了锂掺杂含量对能带结构的影响和电荷迁移的变化,以解释掺杂聚乙炔的绝缘体—导体变化过程及其导电机理。The purpose of this paper is to calculate the conduction and valence band structures of pure and Li-doped (CH)_x by using LCAO-SCF ab initio Crystal Orbital (CO) method, to discuss the effect of Li-doping on the band structures, and the changes of charge transfer in carbon chain, so as to exulain the insulator-conductor transition and the conducting mechanism of (CH)_x. The two unit cells C_6H_6Li and C_4H_4Li are used to represent doping levels of 16.7% and 25%. The calculated results indicate that the undoped (CH)_x is an insulator near to semi-con- ductors. For the doped C_6H_6Li and C_4H_4Li systems, the conduction bands rise while the widths decrease, which cause the decreasing of the gaps between conduction and valence bands (reduce to 0.597 eV and 0.460 eV respectively). The results show that the two doped systems being calcu- lated are all conductors. It is evident that doping brought about the transformation from insula- tor to conductor. After being doped with Li, the energies of valence bands of (CH)_x increase, while those of conduction bands keep almost unchanged, and which cause the decrease of the energy gaps. Several bands which near the conduction and valence bands are to some degree af- fccted by dopants, while the others are much less affected. The results show that the charge distribution in carbon atoms is well-distributed and there is no charge transfer in carbon chain in undoped systems. While in Li-doped ones, unequal charge distribution in carbon atoms brings about the charged domain. And the charged domain on carbon chain of (CH)_x caused by doping with Li produce charged soliton and increase the concentration of the charged soliton which results in the high conductivity of doped polyacetylene.

关 键 词：聚乙炔 锂掺杂聚乙炔 能带结构 

分 类 号：O632.17[理学—高分子化学]