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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. Kurt Kremer Max Planck-Institut für Polymerforschung Ackermannweg 10 D-55128 Mainz Tel: +49 6131 379140 Fax: +49 6131 379340 Secr: +49 6131 379141 Mail: kremer@mpip-mainz.mpg.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 B4: Equilibrium and non-equilibrium processes in open systems via adaptive resolution simulations Computational soft matter constitutes a major application area for simulations, with extraordinary conceptual and practical relevance. Due to the systems’ intrinsic complexity, a considerable effort in this area has focused on investigating somewhat idealised models, e.g., consisting of a few essential molecular species in explicit or implicit solvent. In reality, even the simplest experimentally relevant systems, such as (bio)macromolecules in aqueous mixtures and nanochannels, are far more complex, involving many interacting species, evolving under open-boundary and non-equilibrium conditions. Increasing the complexity and detail of the computational model for these systems poses a significant challenge. Indeed, the interplay of interactions and processes spanning a wide range of length and time scales requires a multiscale approach, including methods resolving quantum, classical, coarse-grained and continuum degrees of resolution. However, it is often the case that a high-resolution method is only […]

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 A6: Coarse-grained models for dynamically asymmetric liquid mixtures under non-equilibrium conditions he main goal of this project is to gain better insight into the mapping of time-dependent properties of complex molecular systems, when studied using multiscale simulations. While the mapping of length scales is inherently defined by the coarse-graining procedure, the mapping of dynamic processes involves a complex combination of factors due to both the removal of degrees of freedom as well as approximations made in determining the coarse-grained (CG) interactions based on a reference all-atom (AA) model. As a consequence, the development of dynamically-consistent CG models is particularly challenging when various dynamic processes on different time scales coexist. To investigate these issues, we have focused on two important classes of systems, liquid crystals (LCs) and ionic liquids (ILs), which pair technological relevance with appropriate dynamics, and still show well defined modes of motion despite their significant complexity. In […]

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 […]