Anisotropic conductivity of undoped and [FeCl4]-doped trans-polyacetylene

EHMO/CO (crystal orbital) quantum chemical methods were used to calculate the two-dimensional (2D) energy band structures of highly oriented trans-polyacetylene (PA) undoped and doped with [FeCl₄]⁻. The band gaps (E_g) of undoped PA in directions parallel and perpendicular to the oriented direction were 1.195 and 3.040 eV, respectively, and that of doped PA with [FeCl₄]⁻ were 0.0223 and 0.0504 eV, respectively. Based on the calculational results, the changes in conductive properties from undoped PA to [FeCl₄]⁻ doped PA could be interpreted. The conductivity anisotropy ratio σ/σ decreased when PA was doped by [FeCl₄]⁻, because the PA chain and the dopant showed a strong interchain coupling. The theoretical results for undoped and doped PA were in good agreement with the experiment.