Breathers and Photoinduced Absorption in Polyacetylene

The dynamics of trans-polyacetylene is studied within the adiabatic model of Su, Schrieffer, and Heeger. A single soliton has a maximum velocity, $v_m$, which can be higher than the sound velocity. A long-time simulation shows that, from an initial electron-hole pair, a soliton and antisoliton emerge with velocities $\pm v_m$ and that a persistent breather is left behind. This breather may account for the high-energy intragap structure observed in photoinduced absorption, including isotope dependence.