Worm-like filaments that are propelled homogeneously along their tangentvector are studied by Brownian dynamics simulations. Systems in two dimensionsare investigated, corresponding to filaments adsorbed to interfaces orsurfaces. A large parameter space covering weak and strong propulsion, as wellas flexible and stiff filaments is explored. For strongly propelled andflexible filaments, the free-swimming filaments spontaneously form stablespirals. The propulsion force has a strong impact on dynamic properties, suchas the rotational and translational mean square displacement and the rate ofconformational sampling. In particular, when the active self-propulsiondominates thermal diffusion, but is too weak for spiral formation, therotational diffusion coefficient has an activity-induced contribution given by$v_c/\xi_P$, where $v_c$ is the contour velocity and $\xi_P$ the persistencelength. In contrast, structural properties are hardly affected by the activityof the system, as long as no spirals form. The model mimics common features ofbiological systems, such as microtubules and actin filaments on motility assaysor slender bacteria, and artificially designed microswimmers.
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