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Project A8: Roberto – Improved dynamics in hybrid particle-field molecular dynamics simulations of polymers We pursue one of the approaches to generate coarse-grained polymer models with correct dynamical properties. If such models can be made predictive for, say, polymer melt viscosities and other rheological characteristics they will make their important contribution toward, e.g., energy-efficient plastics processing or mechanical recycling of plastics waste. In funding period 2 (FP2), we have developed and implemented the Roberto method, a combination of hybrid-particle-field (hPF) molecular dynamics and slip-springs. The hPF method by itself is computationally fast, yet it allows coarse-grained or even atomistic accuracy for the base models. It performs excellent for static polymer properties, but provides a qualitatively wrong molecular mobility. As the field treatment of intermolecular interactions makes them effectively soft-core, atoms can superpose, and polymer chains can cut through one another. The artificial dynamics is remedied by the slip-springs, which restore […]

Project A9: Coarse grained non-equilibrium dynamics of active soft matter Active colloids can self-propel in an unbiased solvent and provide a paradigmatic example of non-equilibrium soft matter. They have received enormous attention in recent years, partly for their rich ability to form dynamic structures such as living crystals, self-organized super-rotor assemblies, and travelling wave patterns. To a large extent, these dynamic structures are now known to hinge on the unusual hydrodynamic interactions among active colloids as well as on the phoretic cross-interactions which hinge on the action of a phoretic field (concentration, temperature) gradient due to a certain colloid on other colloids in the system. These interactions are in general long-ranged, confinement-dependent, non-reciprocal, non-instantaneous and non-pair-wise. However, despite their importance in generic experiments with active colloids, many key aspects of these interactions are still not well understood. To improve our corresponding understanding, the overarching goal of the present project is […]

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 […]

Integrated research training group (IRTG) The integrated research training group (IRTG) of the TRR 146 provides a joint structured graduate education in the area of Computational Materials Science for the graduate students and young postdocs in the TRR 146 as well as other interested candidates working in related areas. The goals of the IRTG are threefold: 1) to provide students with the interdisciplinary background required for the research activities in the TRR 146, and to prepare them for a possible career in the area of theoretical Materials Sciences 2) to ensure common standards in the education of all graduate students in the TRR 146 by means of a well structured supervision and management program, 3) to establish and strengthen links within the TRR 146 already at the level of graduate students and young postdoctoral researchers. Special emphasis is placed on promoting exchange between groups within and outside of the TRR […]