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DY: Dynamik und Statistische Physik

DY 45: Soft Matter

DY 45.1: Talk

Thursday, March 30, 2006, 14:30–14:45, SCH 251

Coil-globule and globule-globule transition of a three-dimensional, flexible homopolymer — •Thomas Strauch, Federica Rampf, Kurt Binder, and Wolfgang Paul — Institute for Physics, Johannes Gutenberg University, 55099 Mainz Germany

We present simulation results for the phase behavior of a flexible homopolymer using the Wang-Landau sampling algorithm. The chain is modeled with the bond-fluctuation model with an attractive square well interaction between the monomers. For finite chain length the model shows a two stage collapse, from the coil state to the globular state followed by a crystallization at temperatures beneath the $∖theta$-temperature. In a recently published investigation by F. Rampf, W. Paul and K. Binder on this model, it was shown that for interaction range $∖sqrt{6}$ the coil-globule phase transition and the crystallization phase transition coincide in the thermodynamic limit.

In order to check the general validity of this phase behavior we investigated a system with longer interaction range, which should stabilize the liquid phase because of entropic effects. We show that in our model with interaction range of $∖sqrt{10}$ the liquid phase will exist also in the thermodynamic limit. The transition temperatures do not coincide.

The crystal structure in the ground state displays a mixture of hexagonal and cubic packing.