Soliton diffusion intrans-polyacetylene

We have calculated acoustic-phonon scattering and the resulting intrachain diffusion constant ${\mathrm{D}}_{\mathrm{?}}$ for neutral solitons in trans-polyacetylene. The result, with no arbitrary parameters, agrees with ${\mathrm{D}}_{\mathrm{?}}$ determined by magnetic resonance experiments from ∼150 to 300 K. The more rapid decrease with decreasing temperature seen below 150 K can be obtained with the introduction of a barrier-to-soliton motion of 0.01 eV. Such barriers may result from remanent cis linkages in the Shirakawa trans-polyacetylene used for the experiments.