Acoustic effects on the soliton lattice in polyacetylene

Abstract

Using perturbation theory for a small acoustic-phonon velocity in the context of a quasi-realistic model, the authors present a self-consistent computation of acoustic-phonon effects on the shape and dynamics of the soliton-lattice solution of the Takayama-Liu-Maki model for trans-polyacetylene. As in the one-soliton sector, they find that, although the shape of the soliton lattice is only slightly modified, acoustic effects induce constant motion of the lattice across the linear chain of C-H groups. The constant velocity is the same as in the one-soliton case. Considerations on the zero mode of the model are also presented. In the limit of large soliton lattice constant, the authors recover the physics of the one-soliton sector. Comments on internal soliton shape oscillations are finally made.