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DY: Fachverband Dynamik und Statistische Physik

DY 24: Poster I

DY 24.42: Poster

Mittwoch, 28. März 2007, 16:00–18:00, Poster D

A microscopic view on the Stokes--Einstein relation: anomalous translational and rotational motion of macromolecules in solution — •Alexander Uvarov and Stephan Fritzsche — Institut für Physik, Universität Kassel, D--34132 Kassel, Germany; uvarov@physik.uni-kassel.de.

In this contribution, we re-analyze the translational and rotational diffusion of non-rigid macromolecules in solution, starting from the microscopic view point. If a molecule is immersed into a solvent, its shape and dynamical behaviour will depend not only on the interaction among the individual beads but will be affected also by the solvent particles. Phenomenologically, the dynamical properties of the macromolecules are hereby described in terms of the friction and diffusion coefficients which follow the known Stokes--Einstein relation (SER).

By using a semi--phenomenological expression, derived for the friction of macromolecules [1], we calculate the boundary and diffusion coefficients of the free macromolecule as well as the orientation and relaxation correlation function of the non-rigid macromolecule immobilized on a surface [1, 2]. When compared with modern experiment [3] and dynamical simulations [4], excellent agreement is found even for low temperatures of the system when SER can not be apply.

[1] A. Uvarov and S. Fritzsche, PRE73, 011111 (2006); PRL, submitted (2006). [2] A. Uvarov and S. Fritzsche, JCM 121(13), 6561 (2004); Progr. Colloid and Polymer Science 133, 95 (2006). [3] B. Chen, E. Sigmund and W. Halperin, PRL 96, 145502 (2006). [4] J. Schmidt and J. Skinner, JPC B. 108, 6767 (2004)