Berlin 2008 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: POSTERS Dynamics and Diffusion

CPP 8.16: Poster

Monday, February 25, 2008, 16:45–19:00, Poster A

Soft spots of hard spheres — •Erik Lange — University of Konstanz

The influence of the potential shape on the structure and dynamics of a colloidal suspension has been of longstanding interest. We use simulations to tackle this question from a new angle.

Exploiting molecular dynamics simulations we find strong differences in the local structure for different potentials. Even a rescaling with respect to the distance from the freezing point does not reconcile this disagreement. However the structure factor

shows a remarkable indifference towards subtleties in the potential.

The fact that a number of different systems display the same structural property suggests a closer look at the structural relaxation. As a result our work provides a clear tool to predict where differences should be negligible.

Indeed the longtime diffusion coefficients coincide as well as the stress-stress correlation at intermediate to long times.

So this is an approach that makes it clearer where softness matters and where hard spheres have soft spots.