Extended Fluctuation-Dissipation Theorem for Driven Colloidal Suspensions

• Applicants: Professor Dr. Udo Seifert; Professor Dr. Thomas Speck
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2008 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 60433802

The fluctuation-dissipation theorem is both of great practical importance for the calculation of transport properties from computer simulations in a wide range of applications as well as of fundamental theoretical interest. So far these calculations have been mainly restricted to equilibrium. During the first funding period we have shown how to extend the fluctuation-dissipation theorem to non-equilibrium steady states involving only measurable quantities. Based on this result we will study a model colloidal suspension driven into non-equilibrium by simple shear flow. We will test to which extent a simple description in terms of an „effective temperature“ is feasible. The influence of flow-induced hydrodynamic interactions between particles on these new fluctuation-dissipation relations will be determined. As a concrete application we will prepare a special state which is only possible in non-equilibrium – a shear-melted suspension – and study the interplay of single-particle diffusion and mobility through our generalized fluctuation-dissipation theorem.

• DFG Programme: Research Grants