Abstract: The effects of Site-type impurity potential which includes isotropic and anisotropic conditions on the electronic states in doped trans-polyacetylene have been calculated numerically by SSH model. For isotropic condition, the results have shown that the Site-type impurity potential can break down the symmetry of midgap state. In addition, changing the spacing of charged impurity ions to the chain only causes the variation of soliton state, however, the degree of localization of soliton is not changed at all. Further study has indicated that a marked variation in the electronic states of trans-PA is caused by the anisotropic impurity potential. In particular, when the magnitude of the anisotropic degree γ is larger than 2.5, the degree of localization for these soliton states decreases rapidly.

Key words: trans-Polyacetylene chain, SSH model, Site-type impurity potential, inverse participation ratio

摘要： 利用SSH模型讨论了Site-type杂质势对反式聚乙炔(trans-PA)电子态的影响。具体计算表明：对各向同性情况，Site-type杂质势破坏了电子能谱的对称性，并使孤子能级发生移动，随着杂质离子与反式聚乙炔链间距的变化，它将引起孤子能级的变动。但不影响孤子局域化程度；而各向异性Site-type杂质势的不均匀性对trans-PA的电子能谱及孤子局域化程度影响较大。

关键词: 反式聚乙炔链, SSH模型, Site-type杂质势, 局域化因子IPR