碱式聚苯胺的小尺寸效应

Small Size Effect in Basic Polyaniline

利用改进的Ginder-Epstein模型计算了碱式聚苯胺在不同链长的自洽变分基态,结果表明:体系的几何结构和电子结构不仅与链长N有关,而且与体系单体数目的结构有关.4n+2体系与4n体系有不同的电子态;当N<40,苯环扭角和能隙随N的减小而增大,醌环扭角和键序波幅却随N的减小而减小;当N>>40,这些差异都消失,体系趋于稳定.

The serf-consistent-variation ground states of basic polyaniline with various chain lengths are investigated by the extend- ed Ginder-Epstein model. The results show that the geometry structure and the electronic structure of the polymer are related to not only the chain length N, but also the structure of monomer number. 4n ＋ 2 and 4n systems possess different electronic states. When N 〈 40, the torsion angles of benzenoid rings and the band gap increase with decreasing N, while the torsion angle and the bond order wave am- plitude decrease with the decreasing N. When N≥40, those diversities all disappear, and the structure of the polymer tends to stability.