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DY: Dynamik und Statistische Physik

DY 22: Polymere

DY 22.1: Fachvortrag

Donnerstag, 20. März 1997, 15:30–16:00, R1

Debye-Hückel polyelectrolytes: Field theory and simulations — •Kurt Kremer, Tanniemola Liverpool, Uwe Micka, and Michael Stapper — Max-Planck-Institut für Polymerforschung, Postfach 3184, 55021 Mainz

We present extensive simulations and a field-theoretic renormalization group (RG) analysis of a single, flexible, weakly charged Debye-Hückel polyelectrolyte chain in a θ-solvent. Our approaches show that the essential physics is given by an interplay between screening length and chain length. A combination of MC- & MD-methods is used to simulate the basic model: monovalently charged monomers with Debye-Hückel interaction coupled by harmonic springs [1]. The structural properties of the chains were examined showing strong discrepancies to all previous analytical approaches. Especially the persistence length shows a sublinear dependence on the screening parameter, while exponents of 2 or 1 were predicted. The RG analysis is based on a Hamiltonean with two fields, one characterises the polymer density (de Gennes field) and the other one the electrostatic interaction. We have calculated the mean square end-to-end distance and shown that it is a scaling function of those two interplaying length scales [2]. A detailed comparison of field theory and simulations will be presented.

[1] U. Micka & K. Kremer, Phys. Rev. E, 54 (3), 2653 (1996)

[2] T. B. Liverpool & M. Stapper, submitted