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Project B8 (N): Hydrodynamic Simulation of Passive and Active Janus Particles Janus particles are colloidal particles whose surface has been modified differently in different locations, creating so-called patches. The patches are designed in a way to generate directional interactions between the Janus particles. Janus particles, therefore, often self-assemble into ordered structures, commonly referred to as lattices or crystal structures, even though the system still is a colloidal solution. By variation of the chemical nature, size and location of the patches, a rich set of lattice structures is accessible. In our work so far, we have focused on triblock Janus particles, which carry attractive van-der-Waals patches on the poles and repulsive electrostatic charges around the equator. We developed a detailed dissipative-particle dynamics model for them, which includes surface chemistry and explicit solvent molecules. With this model and our newly devised adaptive metadynamics method, we could clarify their self-assembly into two-dimensional ordered […]

Prof. Dr. Martin Hanke-Bourgeois Institut für Mathematik Universität Mainz Staudingerweg 9 D-55128 Mainz Tel: +49 6131 39 22528 Fax: +49 6131 39 23331 Mail: hanke@mathematik.uni-mainz.de Further information

Prof. Dr. Marialore Sulpizi Institut für Physik Universität Mainz Staudingerweg 7 D-55128 Mainz Tel: +49 6131 39 23641 Fax: +49 6131 39 25441 Mail: sulpizi@uni-mainz.de Further information

Project A3: Coarse-graining frequency-dependent phenomena and memory in colloidal systems The purpose of this project is to develop numerical strategies for dynamic coarse-graining in situations where the separation of time scales is incomplete and memory effects are important. This entails the reconstruction of coarse-grained dynamical equations that include memory (generalized Langevin equations, GLE), the efficient simulation of coarse-grained models with memory and the application to colloidal dispersions at equilibrium and non-equilibrium. This project is complementary to project A2, where related problems are addressed in the context of dynamic coarse-graining of molecular liquids. In the second funding period, we have extended our previous work on iterative memory reconstruction for single colloids (first funding period) to systems containing multiple colloids, where pair memory effects must be taken into account. A benchmark simulation of 125 colloids in solution showed that a speedup of at least three orders of magnitude can be obtained by […]

Project A4 (Completed): Understanding Water Relaxation Dynamics at Interfaces The aim of the project is to develop multiscale approaches to understand the mechanisms of vibrational energy relaxation in water at interfaces and in confined environment. In the first funding period, we have developed an efficient method to describe molecular vibrational relaxation based on single molecule excitations and the use of new descriptors. In the second funding period, we plan to include nuclear quantum effects (NQEs), which may be important in water. We aim to develop a multi resolution scheme where the electronic structure is included with an effective force field, which accurately reproduces high-level ab initio calculations, while the NQEs are explicitly addressed with the path integral formalism. This project has ended in June 2022.

Project B1: Inverse problems in coarse-grained particle simulations Coarse-graining (CG) methods are an indispensable tool in computational materials science, but the associated upscaling and downscaling processes have to be designed with great care to allow for a proper interpretation of the computed results. Each of these interscale transfers comes along with important inverse problems to be resolved, most of which are ill-posed, or ill-conditioned at the very least. The purpose of this project is to apply rigorous techniques from the mathematical field of inverse and ill-posed problems to attack these fundamental problems in the multiscale simulation of soft matter, and to provide a mathematically rigorous foundation of existing and/or new upscaling processes. n the first two funding phases we have developed the mathematical foundation for a rigorous analysis of iterative methods that are currently being used for the computation of effective pair potentials of sophisticated CG models. We have used […]

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TRR 146: Multiscale Simulation Methods for Soft Matter Systems Multiscale modeling is a central topic in theoretical condensed matter physics and materials science. One prominent class of materials, whose properties can rarely be understood on one length scale and one time scale alone, is soft matter. The properties of soft materials are determined by an intricate interplay of energy and entropy, and minute changes of molecular interactions may lead to massive changes of the system’s macroscopic properties. In our collaborative research center (CRC TRR 146), we plan to tackle some of the most pressing problems in multiscale modeling in a joint effort of physicists, chemists, applied mathematicians, and computer scientists. The TRR 146 receives funding from the german science foundation (DFG) since October 2014. We address three major challenges: (A) Dynamics In the past, multiscale coarse-graining approaches have to a large extent focused on static equilibrium properties. However, a thorough […]