Dynamics of solitons in polyacetylene in the step-potential model

Abstract

In treating the motion of solitonic exitations in polyacetylene Newton's equation is used to approximate the lattice dynamics. The force field is obtained from the deviation of the π-electron densities in the bonds from their equilibrium densities. The π-electron density distributions are evaluated with the step-potential model of a nearly free π-electron coupled to the lattice distortion. Kinks move frictionless for velocities up to three times the velocity of sound and shake off phonons at higher velocities. Excitation leads to a localized defect, which is breathing and later evolving into a kink and an anti-kink moving apart. Scattered neutral kinks are either trapped or repel each other depending on the occupation of their states.