  We consider the motion of semiflexible polymers in double-well potentials. We
calculate shape, energy, and effective diffusion constant of kink excitations,
and in particular their dependence on the bending rigidity of the semiflexible
polymer. For symmetric potentials, the kink motion is purely diffusive whereas
kink motion becomes directed in the presence of a driving force on the polymer.
We determine the average velocity of the semiflexible polymer based on the kink
dynamics. The Kramers escape over the potential barriers proceeds by nucleation
and diffusive motion of kink-antikink pairs, the relaxation to the straight
configuration by annihilation of kink-antikink pairs. Our results apply to the
activated motion of biopolymers such as DNA and actin filaments or synthetic
polyelectrolytes on structured substrates.
