Controlling Bending and Twisting of Conjugated Polymers via Solitons

A strong generic coupling between self-localized solitons and conformations of a π-conjugated polymer chain is demonstrated through ab initio calculations and the underlying mechanisms revealed by using an extended Hubbard model. We show that significant chain bending and twisting of trans- and cis-polyacetylene result from torque imbalances among atom-centered orbitals and the steric instability at single-bond cis-centers, respectively. The soliton-induced conformational effects create sufficient strains to provide an intrinsic high-strain-rate actuation mechanism in optical excitation processes.