中国物理B ›› 2010, Vol. 19 ›› Issue (12): 127105-127105.doi: 10.1088/1674-1056/19/12/127105

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Effects of polarons on static polarizabilities and second order hyperpolarizabilities of conjugated polymers

孟艳1, 邸冰1, 王淑玲1, 安忠1, 王亚东2   

  1. (1)College of Physics, Hebei Normal University, Shijiazhuang 050016, China; Hebei Advanced Thin Films Laboratory, Shijiazhuang 050016, China; (2)College of Physics, Hebei Normal University, Shijiazhuang 050016, China; Hebei Advanced Thin Films Laboratory, Shijiazhuang 050016, China; Zhangjiakou Vocational and Technical College, Zhangjiakou 075051, China
  • 收稿日期:2010-06-20 修回日期:2010-07-24 出版日期:2010-12-15 发布日期:2010-12-15
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 10574037), the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-05-0262), the Hebei Provincial Outstanding Youth Science Fund (Grant No. A2009001512), the Key Project of Ministry of Education of China (Grant No. 210021), the Natural Science Fund of Hebei Province, China (Grant No. A2010000357), and the Educational Commission of Hebei Province, China (Grant No. 2007124).

Effects of polarons on static polarizabilities and second order hyperpolarizabilities of conjugated polymers

Wang Ya-Dong(王亚东)a)b)c), Meng Yan(孟艳) a)b), Di Bing(邸冰)a)b), Wang Shu-Ling(王淑玲)a)b), and An Zhong(安忠)a)b)†   

  1. a College of Physics, Hebei Normal University, Shijiazhuang 050016, China; b Hebei Advanced Thin Films Laboratory, Shijiazhuang 050016, China; Zhangjiakou Vocational and Technical College, Zhangjiakou 075051, China
  • Received:2010-06-20 Revised:2010-07-24 Online:2010-12-15 Published:2010-12-15
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 10574037), the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-05-0262), the Hebei Provincial Outstanding Youth Science Fund (Grant No. A2009001512), the Key Project of Ministry of Education of China (Grant No. 210021), the Natural Science Fund of Hebei Province, China (Grant No. A2010000357), and the Educational Commission of Hebei Province, China (Grant No. 2007124).

摘要: According to the one-dimensional tight-binding SuSchrieffer–Heeger model, we have investigated the effects of charged polarons on the static polarizability, αxx, and the second order hyperpolarizabilities, γxxxx, of conjugated polymers. Our results are consistent qualitatively with previous ab initio and semi-empirical calculations. The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives. Furthermore, combining the Su–Schrieffer–Heeger model and the extended Hubbard model, we have investigated systematically the effects of electron–electron interactions on αxx and γxxxx of charged polymer chains. For a fixed value of the nearest-neighbour interaction V, the values of αxx and γxxxx increase as the on-site Coulomb interaction U increases for Uc and decrease with U for U >Uc, where Uc is a critical value of U at which the static polarizability or the second order hyperpolarizability reaches a maximal value of αmax or γmax. It is found that the effect of the e–e interaction on the value of αxx is dependent on the ratio between U and V for either a short or a long charged polymer. Whereas, that effect on the value of γxxxx is sensitive both to the ratio of U to V and to the size of the molecule.

Abstract: According to the one-dimensional tight-binding SuSchrieffer–Heeger model, we have investigated the effects of charged polarons on the static polarizability, $\alpha$xx, and the second order hyperpolarizabilities, $\gamma$xxxx, of conjugated polymers. Our results are consistent qualitatively with previous ab initio and semi-empirical calculations. The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives. Furthermore, combining the Su–Schrieffer–Heeger model and the extended Hubbard model, we have investigated systematically the effects of electron–electron interactions on $\alpha$xx and $\gamma$xxxx of charged polymer chains. For a fixed value of the nearest-neighbour interaction V,  the values of $\alpha$xx and $\gamma$xxxx  increase as the on-site Coulomb interaction U  increases for U<Uc  and decrease with U for U >Uc, where Uc is a critical value of U at which the static polarizability or the second order hyperpolarizability reaches a maximal value of $\alpha$max or $\gamma$max. It is found that the effect of the e–e interaction on the value of $\gamma$xx is dependent on the ratio between U and V for either a short or a long charged polymer. Whereas, that effect on the value of $\gamma$xxxx is sensitive both to the ratio of U to V and to the size of the molecule.

Key words: polaron, nonlinear optics, conjugated polymer

中图分类号: 

  • 7138