高取向顺式聚乙炔导电性能的各向异性

Anisotropies of Highly Oriented Undoped and Iodine-doped cis-Polyacetylene

用EHMO/CO方法计算了高取向顺式聚乙炔及其碘掺杂物的二维能带结构,并据此讨论了它们导电性能的各向异性问题,结果表明平行于分子链方向的电导率与垂直于该方向的电导率之比(σ‖/σ⊥)取决于这两个方向上的价带宽和导带宽.碘掺杂后σ‖/σ⊥下降的原因是链间耦合增加.碘掺杂后的顺式聚乙炔是一个键间相互作用微弱的二维或三维体系.计算结果与实验结果较好地吻合.

The two-dimensional energy-band structures of highly oriented undoped and iodine-doped cis-polyacetylene are calculated by EHMO/CO method in this paper, and their electronic anisotropies are discussed. The ratio between the conductivity in the direction parallel to the molecular chain and that in the direction perpendicular to the molecular chain (σ∥/σ⊥) depends on the ratio between the valence band widths and the conduction band widths in the two directions. The σ∥/σ⊥ decreases after iodine-doping as a result of the increase in interchain coupling. The results are in good agreement with experimental ones.