Self-assembly and self-organisation in fluctuating systems of dipolar colloids: Towards a coarse-grained theoretical description

• Applicant: Professorin Dr. Sabine Klapp
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 449485571

This project is concerned with the investigation of dynamical phenomena in selfassembled colloidal structures in equilibrium and in nonequilibrium. In the structures of interest, bonds between particles are not of chemical nature, but arise from directional, dipolar or multipolar, interactions. As a consequence, thermal fluctuations play a major role for play a major role for the relaxation dynamics, as well as for the self-organization in nonequilibrium. The investigations will be carried out based on computer simulations of suitable model systems without explicit solvent. The specific models considered are inspired by colloidal physics; however, self-assembly in presence of fluctuations also plays a key role in various biological contexts, such as protein assembly and aggregation of microorganisms. The main part of the project focuses on the formation of system-spanning networks and the corresponding relaxation dynamics towards equilibrium. Here, we will perform particle-resolved simulations to elucidate in detail the translational and orientational single-particle dynamics. The major goal, however, is to construct a coarse-grained, stochastic description of the dynamics based on a reduction of the continuous many-particle dynamics into a discrete set of states. For the self-assembling systems of interest, this is an innovative approach from which we expect a deeper understanding concerning relaxation times and the pathways of the aggregation process. Further, we will extend our research to the self-assembly (selforganization) of nonequilibrium dipolar systems, particularly the formation of clusters of active dipolar particles which involve a self-propulsion mechanism. Of particular interest is the role of orientational fluctuations and hydrodynamics. As a long-term goal, we also aim at developing coarse-graining strategies (based on state discretization) for such nonequilibrium systems.

• DFG Programme: Research Grants