Europhys. Lett.
Volume 76, Number 4, November 2006
Page(s) 670 - 676
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 20 October 2006
Europhys. Lett., 76 (4), pp. 670-676 (2006)
DOI: 10.1209/epl/i2006-10332-1

Size dependence of second-order hyperpolarizability of finite periodic chains under Su-Schrieffer-Heeger model

S. 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 $\gamma_N(-3\omega;\omega,\omega,\omega)$ 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 $\gamma_N$. Our study shows that $\gamma_N/N$ is nonmonotonic with N and that the nonmonotonicity is caused by the dominant contribution of the intraband transition to $\gamma_N$ 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.

© EDP Sciences 2006