Size dependence of second-order hyperpolarizability of finite periodic chains under Su-Schrieffer-Heeger modelS. D. Jiang1 and M. Z. Xu2
1 Department of Mathematical Sciences, New Jersey Institute of Technology Newark, NJ 07102, USA
2 Department of Chemistry, New York University - New York, NY 10003, USA
received 14 April 2006; accepted in final form 29 September 2006
published online 20 October 2006
The second hyperpolarizability of N double-bond finite chain of trans-polyacetylene is analyzed using the Su-Schrieffer-Heeger model to explain qualitative features of the size dependence behavior of . Our study shows that is nonmonotonic with N and that the nonmonotonicity is caused by the dominant contribution of the intraband transition to in polyenes. Several important physical effects are discussed to reduce quantitative discrepancies between experimental and our results.
78.66.Qn - Polymers; organic compounds.
42.65.An - Optical susceptibility, hyperpolarizability.
78.20.Bh - Theory, models, and numerical simulation.
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