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Vortragende Person/Vortragende Personen:
Dr. Daniel de las Heras Diaz-Plaza, Physikalisches Institut, Universität Bayreuth

External fields are often used to generate structure and sustain flows in colloidal systems. The response of colloids to external perturbations is often complex due to the many-body internal interactions between the particles. Here, I will discuss the response of colloidal systems to a gravitational field, a time- and position-dependent magnetic field, and a random non-conservative external field. A simple gravitational field can lead to a wealth of new phenomena in colloidal mixtures, such as the occurrence of several stacks of different bulk phases in a cuvette [1]. Using a spatially inhomogeneous magnetic pattern coupled with a time-dependent uniform magnetic field, it is possible to topologically transport a collection of identical colloidal particles independently and simultaneously [2]. Measuring, with computer simulations, the response of the colloidal system to randomized external fields allows us to predict the dynamics of the system at the one-body level [3]. We use a neural network to learn the kinematic mapping predicted by power functional theory from the density and velocity profiles to the one-body internal force field. The network accurately represents the functional mapping, allowing us to predict the response of the system to arbitrary external fields. Moreover, due to a local learning approach, we can predict the dynamics in systems much larger than the size of the original simulation box in which the training data were generated.
[1] T. Eckert, M. Schmidt, and D. de las Heras, Commun. Phys., 4, 202, (2021)
[2] N. C. X. Stuhlmüller, F. Farrokhzad, P. Kuswik, F. Stobiecki, M. Urbaniak, S. Akhundzada, A. Ehresmann, T. M. Fischer, and D. de las Heras, Nat. Commun., 14, 7517, (2023)
[3] T. Zimmermann, F. Sammüller, S. Hermann, M. Schmidt, and D. de las Heras, arXiv 2406.03606 (2024)
sfb1432.