电子相互作用和高聚物中的极化子

ELECTRON INTERACTION AND THE POLARON IN POLYMERS 

各种电致发光聚合物具有非简并基态．当电子和空穴注入后，形成的载流子是极化子．极化子的大小和能量决定于电子相互作用．目前大家采用Ｈｕｂｂａｒｄｍｏｄｅｌ来描述聚合物中的电子相互作用，所得到的结果与实验不符．Ｈｕｂｂａｒｄｍｏｄｅｌ和ｅｘｔｅｎｄｅｄＨｕｂｂａｒｄｍｏｄｅｌ对窄能带体系是好的近似，但聚合物是宽能带，反映价键关联的非对角相互作用（在ｅｘｔｅｎｄｅｄＨｕｂｂａｒｄｍｏｄｅｌ中被略去）有重要贡献，特别是在强屏蔽情况下，价键关联与Ｈｕｂｂａｒｄ关联相互竞争。

Abstract Currently, the extended Hubbard model, which is a good approximation only for narrow band system, suggests that the width of polaron in polymer is heavily reduced by the electron electron interaction. However, the polymers possess wide band, so the off diagonal correlation cannot be neglected. We considered the effects of full electron electron correlation on the width and the creation energy of polaron in polymer. In the case of strong screening, our results are greatly different from those of Hubbard model. This suggests that in polymer, the Hubbard model should be gone beyond.