Dresden 2017 – scientific programme

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BP: Fachverband Biologische Physik

BP 52: Topological Problems in the Physics of Polymers, Biopolymers and Fibers I (Joint Focus Session CPP/BP)

BP 52.6: Invited Talk

Thursday, March 23, 2017, 16:45–17:15, ZEU 260

Knots as Stable Topological Order Parameter for Semiflexible Polymers — •Wolfhard Janke and Martin Marenz — Institut für Theoretische Physik, Universität Leipzig, Postfach 100 920, 04009 Leipzig, Germany

We investigate the influence of bending stiffness on the conformational phases of a semiflexible bead-stick homopolymer and present the pseudo-phase diagram for the complete range of semiflexibility, from flexible to stiff. By varying the internal bending stiffness, the model exhibits different pseudo phases like bent, hairpin or toroidal. In particular, we find thermodynamically stable phases characterized by knots of specific topologies. The transitions into these “knotted” phases from other ordered phases are quite unusual in that they display clear phase coexistence but almost no change in the mean total energy and hence no latent heat. It will be explained how we arrive at these intriguing results by computer simulations based on a combination of the replica-exchange Monte Carlo algorithm and the multicanonical method and discussed how one can understand these effects by basic statistical physics reasoning.

M. Marenz and W. Janke, Knots as a Topological Order Parameter for Semiflexible Polymers, Phys. Rev. Lett. 116, 128301 (2016).

M. Marenz and W. Janke, Stable Knots in the Phase Diagram of Semiflexible Polymers: A Topological Order Parameter?, J. Phys.: Conf. Ser. 750, 012006 (2016).