Berlin 2008 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 18: SYMPOSIUM Driven Soft Matter III

CPP 18.5: Talk

Tuesday, February 26, 2008, 17:45–18:00, C 130

Dynamical density functional theory for anisotropic colloidal particles — •Martin Rex, Henricus Herman Wensink, and Hartmut Löwen — Institut für Theoretische Physik II: Weiche Materie, Universität Düsseldorf, Germany

We generalize the formalism of dynamical density functional theory for translational Brownian dynamics towards that of anisotropic colloidal particles which perform both translational and rotational Brownian motion. Using a mean-field approximation for the density functional and a Gaussian-segment model for the rod interaction, the dynamical density functional theory is then applied to a concentrated rod suspension in a confined slab-geometry made by two parallel soft walls. The walls are either expanded or compressed and the relaxation behavior is investigated for an equilibrated starting configuration. We find distinctly different orientational ordering during expansion and compression. During expansion we observe preferential parallel ordering of the rods relative to the wall while during compression there is homeotropic ordering perpendicular to the wall. We find a nonexponential relaxation behavior in time. Furthermore an external field which aligns the rods perpendicular to the walls is turned on or switched off and similar differences in the relaxational dynamics are found. Comparing the theoretical predictions to Brownian dynamics computer simulation data, we find good agreement.