The soliton diffusion due to the coupling to acoustic phonons in polyacetylene is analyzed theoretically within the Su, Schrieffer, and Heeger model. It is shown that in the temperature region $T\ll \frac{1}{2}{\omega }_0$, where ${\omega }_0$ (∼2000 K) is the optical-phonon frequency, the acoustic phonon dominates the soliton damping. Furthermore, for $T\gg T_0$, the single-phonon process dominates the soliton diffusion where $T_0=2m{c}^2$, and $m$ and $c$ are the soliton mass and the acoustic-phonon velocity, respectively. The one-dimensional model predicts the temperature-dependent diffusion constant $D\propto T^{\frac{1}{2}}$, while the three-dimensional model predicts $D\propto T^{-\frac{1}{2}}$. The latter temperature dependence appears to be consistent with some of the recent nuclear-magnetic-resonance experiments.

Close

PrevNext

View figure in article