# Dresden 2017 – wissenschaftliches Programm

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# CPP: Fachverband Chemische Physik und Polymerphysik

## CPP 60: Focus: Topological Problems in the Physics of Polymers, Biopolymers and Fibers I (joint session BP/CPP, organized by CPP)

### CPP 60.7: Vortrag

### Donnerstag, 23. März 2017, 17:15–17:30, ZEU 260

**An application of the Wang-Landau Monte Carlo method to the modeling of the themal and mechanical behavior of knotted polymer rings in solutions** — •Franco- Ferrari^{1} and Yani Zhao^{2} — ^{1}CASA* and University of Szczecin, Szczecin, Poland — ^{2}Centre of New Technologies, University of Warsaw, Warsaw, Poland

The subject of this seminar are the properties and behavior in solutions of single knotted polymer rings. These polymers are defined on a simple cubic lattice. Their statistical properties are investigated by computing the expectation values of a few observables, namely the specific energy, the specific heat capacity and the gyration radius. In the case in which the chain is stretched by a tensile force directed along the z-axis, the average height of the point in which the force has been applied is measured too. The averages are computed exploiting a variant of the Wang-Landau Monte Carlo method. The algorithm has been suitably accelerated and parallelized in such a way that it is possible to sample a large number (from tens to hundreds of billions) of knot conformations. Several types of knots have been considered, including the trefoil, the figure-eight, the cinquefoil knots and many others. From the performed analysis it turns out that knotted polymer rings have a rich variety of different behaviors that can be used in order to tune the properties of polymer materials containing such knots. For instance, these polymers swell faster or slower when heated depending on the type of the knot and on the kind of interactions between the monomers. During the talk some interesting features of the stress relaxation of knotted polymer rings after the stretching force is removed will also be shown.