Berlin 2008 – wissenschaftliches Programm
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SYMP: Symposium Computational Soft matter physics
SYMP 1: Computational soft matter physics
SYMP 1.7: Vortrag
Donnerstag, 28. Februar 2008, 12:15–12:30, H 0105
Escape transition of grafted polymer chains from a cylindrical tube — •Hsiao-Ping Hsu1, Kurt Binder1, Leonid I. Klushin2, and Alexander M. Skvortsov3 — 1Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany — 2American University of Beirut, Department of Physics, Beirut, Lebanon — 3Chemical-Pharmaceutical Academy, St. Petersburg, Russia.
A grafted polymer chain confined in a finite cylindrical tube of length L and diameter D undergoes an abrupt transition when the number of monomers in the chain, N, reaches a critical value. This problem has the merit that it is potentially very relevant for experiments and application such as the problem of polymer translocation through pores in membranes. In order to check the theoretical prediction based on the Landau free energy approach, we study 3d single polymer chains with one end grafted at the inner wall of a cylindrical tube, by simulating self-avoiding walks on a simple cubic lattice with finite cylindrical confinement. A biased sequential sampling algorithm with re-sampling, similar to the pruned-enriched Rosenbluth method (PERM) is used. The difficulty of obtaining correct samplings for the first-order phase transition is solved by pulling the free chain end with different strength of force out from the tube, and reweighting the biased configuration. We estimate the free energy, the end-to-end distance, the number of imprisoned monomers, the order parameter, and its distribution. It is shown that in the thermodynamic limit, there is a very pronounced jump in several average characteristics. All simulation results are in good agreement with the analytical theory.