Regensburg 2007 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: Diffusion and Transport Processes

CPP 15.1: Vortrag

Dienstag, 27. März 2007, 14:30–14:45, H47

Effect of coarse-graining on the dynamics of fluid mixtures: how important is the structure? — •Jörg Silbermann, Sabine Klapp, and Martin Schoen — Stranski–Laboratorium für Physikalische und Theoretische Chemie, Sekretariat C7, Technische Universität Berlin, Straße des 17. Juni 115, D-10623 Berlin, Germany

We consider a colloidal model suspension consisting of large solute (A) particles immersed in a bath of smaller (B) particles with all interactions being of the Lennard–Jones type. This (reference) system is systematically simplified (coarse–grained) by replacing the original B particles by a reduced number of larger and heavier ones such that the mass and volume fraction of B particles is kept constant. Using Boltzmann inversion we adjust the (effective) intermolecular interactions between A particles in the coarse–grained system such that the static A–A structure of the reference system is preserved. By means of this procedure a whole set of systems is generated all exibiting the same static A–A structure regardless of the degree of coarse–graining. We take the mass ratio of A and B particles to vary between 64 (reference system) and 1. Based on molecular dynamics (MD) computer simulations we identify the effects that coarse–graining of the solvent imposes on typical microscopic time correlation functions characterizing the single–particle and collective dynamics of the solute. Our results [1] indicate that coarse–graining may have a pronounced effect on the dynamics of the solute depending on the total packing fraction of the binary mixture.

[1] J. R. Silbermann et al., Mol. Phys., (2006) submitted.