Soliton clusters inducing insulator-to-metal transition in polyacetylene: a Su-Schrieffer-Heeger model study

The Su-Schrieffer-Heeger (SSH) Hamiltonian has been one of most used models to study the electronic structure of polyacetylene (PA) chains. It has bee n reported in the literature that in the SSH framework a disordered soliton distribution can not produce a metallic regime. However, in this work (usi ng the same SSH model and parameters) we show that this is possible. The ne cessary conditions for true metals (non-vanishing density of states and ext ended wavefunctions around the Fermi level) are obtained for soliton concen tration higher than 6% through soliton segregation (clustering). These resu lts are consistent with recent experimental data supporting disorder as an essential mechanism behind the high conductivity of conducting polymers. (C ) 2001 Elsevier Science B.V. All rights reserved.