s a ketabi - School of Physics, Damghan University of Sciences, Damghan, Iran
n shahtahmasebi - . Department of Physics, School of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran

In this study the nature of transition to metallic regime in trans-polyacetylene (trans-PA) is investigated. Based on SuSchrieffer-Heeger (SSH) model and the use of Continued - Fraction Representation (CFR) as well as Lanczos algorithm procedure, we studied the effects of some selected soliton distributions on the semiconductor-to-metal transition in trans-PA.We found that: i) this transition occurs only when there exists a soliton sublattice in trans-PA, ii) disordered soliton distributions and soliton clustering are the origin of the metallic transition in trans-PA, that is consistent with the experimental data. Our results show that in the presence of correlation between solitons, the disorder in accompanying single soliton distributions plays a crucial role in inducing the transition to metallic regime, so that in contrast to Anderson s localization theorem, the electronic states near the Fermi level are extended, that is the most significant criteria for the metallic regime.

Lanczos algorithm and continued-fraction representation, polyacetylene, disorder and soliton, semiconductor-to-metal transition