@article{HoeflingStraube2025, author = {H{\"o}fling, Felix and Straube, Arthur}, title = {Langevin equations and a geometric integration scheme for the overdamped limit of rotational Brownian motion of axisymmetric particles}, volume = {7}, journal = {Physical Review Research}, arxiv = {http://arxiv.org/abs/2403.04501}, doi = {10.1103/wzdn-29p4}, pages = {043034}, year = {2025}, abstract = {The translational motion of anisotropic or self-propelled colloidal particles is closely linked with the particle's orientation and its rotational Brownian motion. In the overdamped limit, the stochastic evolution of the orientation vector follows a diffusion process on the unit sphere and is characterized by an orientation-dependent ("multiplicative") noise. As a consequence, the corresponding Langevin equation attains different forms depending on whether Itō's or Stratonovich's stochastic calculus is used. We clarify that both forms are equivalent and derive them in a top-down approach from a geometric construction of Brownian motion on the unit sphere, based on infinitesimal random rotations. Our approach suggests further a geometric integration scheme for rotational Brownian motion, which preserves the normalization constraint of the orientation vector exactly. We show that a simple implementation of the scheme, using Gaussian random rotations, converges weakly at order 1 of the integration time step, and we outline an advanced variant of the scheme that is weakly exact for an arbitrarily large time step. Due to a favorable prefactor of the discretization error, already the Gaussian scheme allows for integration time steps that are one order of magnitude larger compared to a commonly used algorithm for rotational Brownian dynamics simulations based on projection on the constraining manifold. For torques originating from constant external fields, we prove by virtue of the Fokker-Planck equation that the constructed diffusion process satisfies detailed balance and converges to the correct equilibrium distribution. The analysis is restricted to time-homogeneous rotational Brownian motion (i.e., a single rotational diffusion constant), which is relevant for axisymmetric particles and also chemically anisotropic spheres, such as self-propelled Janus particles.}, language = {en} } @article{SchaibleWinartoŠkorjancetal.2025, author = {Schaible, Jonas and Winarto, Hanifah and Škorjanc, Viktor and Yoo, Danbi and Zimmermann, Lea and J{\"a}ger, Klaus and Sekulic, Ivan and Schneider, Philipp-Immanuel and Burger, Sven and Wessels, Andreas and Bl{\"a}si, Benedikt and Becker, Christiane}, title = {Optimizing Aesthetic Appearance of Perovskite Solar Cells Using Color Filters}, volume = {9}, journal = {Solar RRL}, publisher = {Wiley}, doi = {10.1002/solr.202400627}, pages = {2400627}, year = {2025}, abstract = {The significance of color aesthetics in photovoltaic (PV) modules gains importance, especially in design-centric applications like building-integrated PVs. Color filters based on distributed Bragg reflectors, consisting of alternating thin-film layers of different refractive indices, can modify the appearance of standard silicon modules. This approach is also extended to optimize the color appearance of emerging PV technologies such as perovskite solar cells, which typically exhibit a less appealing gray-brownish appearance. In this contribution, perovskite solar-cell stacks combined with MorphoColor color filters are presented. Angular-resolved reflectance simulations based on wave optics and ray tracing with experimental data are validated, and the color appearance from various viewing angles is evaluated. Additionally, the impact of individual layers on color appearance and the maximum achievable short-circuit current density in the perovskite solar cell is investigated. By applying Bayesian optimization, the color distance is minimized to the targeted appearance. Tailoring the bridging layers between the color filter and the perovskite solar cell is found to strongly influence the color impression due to the coherently combined color filter and perovskite solar cell. The presented color optimization concept allows to customize the aesthetics of emerging PV thin-film technologies such as perovskite solar cells.}, language = {en} } @misc{RocheBetzYangetal.2024, author = {Roche, L{\´e}o J. and Betz, Fridtjof and Yang, Yuhui and Limame, Imad and Shih, Ching-Wen and Burger, Sven and Reitzenstein, Stephan}, title = {Inside Front Cover: Numerical Investigation of a Coupled Micropillar - Waveguide System for Integrated Quantum Photonic Circuits (Adv. Quantum Technol. 12/2024)}, volume = {7}, journal = {Adv. Quantum Technol.}, doi = {10.1002/qute.202470036}, pages = {2470036}, year = {2024}, language = {en} } @inproceedings{MukherjeeBurgerSiefkeetal.2024, author = {Mukherjee, Deshabrato and Burger, Sven and Siefke, Thomas and Gour, Jeetendra and Bodermann, Bernd and Petrik, Peter}, title = {Modeling of dimensions and sensing properties of gold gratings by spectroscopic ellipsometry and finite element method}, volume = {309}, booktitle = {EPJ Web of Conferences}, doi = {10.1051/epjconf/202430902016}, pages = {02016}, year = {2024}, language = {en} } @article{DjurdjevacConradTonelloZonkeretal.2025, author = {Djurdjevac Conrad, Natasa and Tonello, Elisa and Zonker, Johannes and Siebert, Heike}, title = {Detection of dynamic communities in temporal networks with sparse data}, volume = {10}, journal = {Applied Network Science}, publisher = {Springer International Publishing}, doi = {10.1007/s41109-024-00687-3}, year = {2025}, abstract = {Temporal networks are a powerful tool for studying the dynamic nature of a wide range of real-world complex systems, including social, biological and physical systems. In particular, detection of dynamic communities within these networks can help identify important cohesive structures and fundamental mechanisms driving systems behaviour. However, when working with real-world systems, available data is often limited and sparse, due to missing data on systems entities, their evolution and interactions, as well as uncertainty regarding temporal resolution. This can hinder accurate representation of the system over time and result in incomplete or biased community dynamics. In this paper, we compare established methods for community detection and, using synthetic data experiments and real-world case studies, we evaluate the impact of data sparsity on the quality of identified dynamic communities. Our results give valuable insights on the evolution of systems with sparse data, which are less studied in existing literature, but are frequently encountered in real-world applications.}, language = {en} } @article{ZimperCornalbaDjurdjevacConradetal.2025, author = {Zimper, Sebastian and Cornalba, Federico and Djurdjevac Conrad, Natasa and Djurdjevac, Ana}, title = {On reduced inertial PDE models for Cucker-Smale flocking dynamics}, volume = {481}, journal = {Proceedings of the Royal Society A}, publisher = {Royal Society}, arxiv = {http://arxiv.org/abs/2407.18717}, doi = {https://doi.org/10.1098/rspa.2024.0675}, year = {2025}, abstract = {In particle systems, flocking refers to the phenomenon where particles' individual velocities eventually align. The Cucker-Smale model is a well-known mathematical framework that describes this behaviour. Many continuous descriptions of the Cucker-Smale model use PDEs with both particle position and velocity as independent variables, thus providing a full description of the particles mean-field limit (MFL) dynamics. In this paper, we introduce a novel reduced inertial PDE model consisting of two equations that depend solely on particle position. In contrast to other reduced models, ours is not derived from the MFL, but directly includes the model reduction at the level of the empirical densities, thus allowing for a straightforward connection to the underlying particle dynamics. We present a thorough analytical investigation of our reduced model, showing that: firstly, our reduced PDE satisfies a natural and interpretable continuous definition of flocking; secondly, in specific cases, we can fully quantify the discrepancy between PDE solution and particle system. Our theoretical results are supported by numerical simulations.}, language = {en} } @article{FischbachBetzAsadovaetal.2025, author = {Fischbach, Jan David and Betz, Fridtjof and Asadova, Nigar and Tassan, Pietro and Urbonas, Darius and St{\"o}ferle, Thilo and Mahrt, Rainer F. and Burger, Sven and Rockstuhl, Carsten and Binkowski, Felix and Sturges, Thomas Jebb}, title = {A framework to compute resonances arising from multiple scattering}, volume = {8}, journal = {Adv. Theory Simul.}, arxiv = {http://arxiv.org/abs/2409.05563}, doi = {10.1002/adts.202400989}, pages = {2400989}, year = {2025}, language = {en} } @article{JaegerTejadaBerwigetal.2025, author = {J{\"a}ger, Klaus and Tejada, Alvarjo and Berwig, Sebastian and Hammerschmidt, Martin and Tockhorn, Philipp and Albrecht, Steve and Becker, Christiane}, title = {Optical Simulations of Nanotextured All-Perovskite Tandem Solar Cells}, volume = {8}, journal = {Adv. Theory Simul.}, doi = {10.1002/adts.202400724}, pages = {2400724}, year = {2025}, language = {en} } @inproceedings{BinkowskiBetzHammerschmidtetal.2024, author = {Binkowski, Felix and Betz, Fridtjof and Hammerschmidt, Martin and Zschiedrich, Lin and Burger, Sven}, title = {Poles and Zeros in Resonant Nano-Photonic Systems}, booktitle = {2024 Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR)}, doi = {10.1109/CLEO-PR60912.2024.10676837}, year = {2024}, language = {en} } @inproceedings{JaegerBurgerAeberhardetal.2024, author = {J{\"a}ger, Klaus and Burger, Sven and Aeberhard, Urs and Llado, Esther Alarcon and Bl{\"a}si, Benedikt and Ehrler, Bruno and Favre, Wilfried and Fejfar, Anton{\´i}n and Gageot, Tristan and Gordon, Ivan and Helmers, Henning and H{\"o}hn, Oliver and Isabella, Olindo and Jošt, Marko and Ledinsk{\´y}, Martin and Mandal, Jyotirmoy and Manley, Phillip and Munoz, Delfina and Lizcano, Juan Camilo Ortiz and Paetzold, Ulrich W. and Raman, Aaswath P. and Sai, Hitoshi and Saive, Rebecca and Schmid, Martina and Yablonovitch, Eli and Becker, Christiane}, title = {A Roadmap on Optics for Terawatt Scale Photovoltaics}, booktitle = {Advanced Photonics Congress 2024}, publisher = {Optica Publishing Group}, doi = {10.1364/SELED.2024.STu2G.5}, pages = {STu2G.5}, year = {2024}, language = {en} } @article{ArmasMerbisMeylahnetal.2025, author = {Armas, Jay and Merbis, Wout and Meylahn, Janusz M and Rafiee Rad, Soroush and del Razo, Mauricio J}, title = {Risk aversion can promote cooperation}, volume = {6}, journal = {Journal of Physics: Complexity}, number = {1}, arxiv = {http://arxiv.org/abs/2306.05971}, doi = {10.1088/2632-072X/adb234}, year = {2025}, abstract = {Cooperative dynamics are central to our understanding of many phenomena in living and complex systems. However, we lack a universal mechanism to explain the emergence of cooperation. We present a novel framework for modelling social dilemma games with an arbitrary number of players by combining reaction networks, methods from quantum mechanics applied to stochastic complex systems, game theory and stochastic simulations of molecular reactions. Using this framework, we propose a novel and robust mechanism for cooperation based on risk aversion that leads to cooperative behaviour in population games. Rather than individuals seeking to maximise payouts in the long run, individuals seek to obtain a minimum set of resources with a given level of confidence and in a limited time span. We show that this mechanism can lead to the emergence of new equilibria in a range of social dilemma games.}, language = {en} } @article{AsadovaAchouriArjasetal.2025, author = {Asadova, Nigar and Achouri, Karim and Arjas, Kristian and Ajugui{\´e}, Baptiste and Aydin, Roland and Baron, Alexandre and Beutel, Dominik and Bodermann, Bernd and Boussaoud, Kaoutar and Burger, Sven and Choi, Minseok and Czajkowski, Krzysztof and Evlyukhin, Andrey B. and Fazel-Najafabadi, Atefeh and Fernandez-Corbaton, Ivan and Garg, Puneet and Globosits, David and Hohenester, Ulrich and Kim, Hongyoon and Kim, Seokwoo and Lalanne, Philippe and Le Ru, Eric C. and Meyer, J{\"o}rg and Mun, Jungho and Patelli, Lorenzo and Pflug, Lukas and Rockstuhl, Carsten and Rho, Junsuk and Rotter, Stefan and Stout, Brian and T{\"o}rm{\"a}, P{\"a}ivi and Trigo, Jorge Olmos and Tristram, Frank and Tsitsas, Nikolaos L. and Vall{\´e}e, Renaud and Vynck, Kevin and Weiss, Thomas and Wiecha, Peter and Wriedt, Thomas and Yannopapas, Vassilios and Yurkin, Maxim A. and Zouros, Grigorios P.}, title = {T-matrix representation of optical scattering response: Suggestion for a data format}, volume = {333}, journal = {J. Quant. Spectrosc. Radiat. Transf.}, arxiv = {http://arxiv.org/abs/2408.10727}, doi = {10.1016/j.jqsrt.2024.109310}, pages = {109310}, year = {2025}, language = {en} } @article{RocheBetzYangetal.2024, author = {Roche, L{\´e}o J. and Betz, Fridtjof and Yang, Yuhui and Limame, Imad and Shih, Ching-Wen and Burger, Sven and Reitzenstein, Stephan}, title = {Numerical Investigation of a Coupled Micropillar - Waveguide System for Integrated Quantum Photonic Circuits}, volume = {7}, journal = {Adv. Quantum Technol.}, doi = {10.1002/qute.202400195}, pages = {2400195}, year = {2024}, language = {en} } @article{BinkowskiBurgerKewes2024, author = {Binkowski, Felix and Burger, Sven and Kewes, G{\"u}nter}, title = {A tiny Drude scatterer can accurately model a coherent emitter in nanophotonics}, volume = {13}, journal = {Nanophotonics}, doi = {10.1515/nanoph-2024-0170}, pages = {4537}, year = {2024}, language = {en} } @article{BernsYildizWinkelmannetal.2025, author = {Berns, Manon and Yildiz, Mirza and Winkelmann, Stefanie and Walter, Alexander}, title = {Independently engaging protein tethers of different length enhance synaptic vesicle trafficking to the plasma membrane}, volume = {603}, journal = {The Journal of Physiology}, number = {20}, doi = {10.1113/JP286651}, pages = {6107 -- 6134}, year = {2025}, abstract = {Synaptic vesicle (SV) trafficking toward the plasma membrane (PM) and subsequent SV maturation are essential for neurotransmitter release. These processes, including SV docking and priming, are coordinated by various proteins, such as SNAREs, Munc13, and Synaptotagmin (Syt), which connect—tether—the SV to the PM. Here, we investigated how tethers of varying lengths mediate SV docking using a simplified mathematical model. The heights of the three tether types—estimated from the structures of the SNARE complex, Munc13, and Syt—defined the SV-to-PM distance ranges for tether formation. Geometric considerations linked SV-to-PM distances to the probability and rate of tether formation. We assumed that SV tethering constrains SV motility and that multiple tethers associate by independent interactions. The model predicted that forming multiple tethers favors shorter SV-to-PM distances. Although tethers acted independently in the model, their geometrical properties often caused sequential assembly, from longer ones (Munc13/Syt), that accelerated SV movement towards the PM, to shorter ones (SNAREs) which stabilized PM-proximal SVs. Modifying tether lengths or numbers affected SV trafficking. The independent implementation of tethering proteins enabled their selective removal to mimic gene knockout situations. This showed that simulated SV-to-PM distance distributions qualitatively aligned with published EM studies upon removal of SNARE and Syt tethers, while Munc13 knockout data were best approximated when assuming additional disruption of SNARE tethers. Thus, while salient features of SV docking can be accounted for by independent tethering alone, our results suggest that functional tether interactions not yet featured in our model are crucial for biological function.}, language = {en} } @misc{BinkowskiBetzHammerschmidtetal.2024, author = {Binkowski, Felix and Betz, Fridtjof and Hammerschmidt, Martin and Zschiedrich, Lin and Burger, Sven}, title = {Source code and simulation results: Resonance modes in microstructured photonic waveguides - Efficient and accurate computation based on AAA rational approximation}, journal = {Zenodo}, doi = {10.5281/zenodo.14202408}, pages = {doi: 10.5281/zenodo.14202408}, year = {2024}, language = {en} } @article{BecksLippoldWinkleretal.2024, author = {Becks, Henrik and Lippold, Lukas and Winkler, Paul and Rohrer, Maximilian and Leusmann, Thorsten and Anton, David and Sprenger, Bjarne and K{\"a}hler, Philipp and Rudenko, Iryna and Andr{\´e}s Arcones, Daniel and Koutsourelakis, Phaedon-Stelios and Unger, J{\"o}rg F. and Weiser, Martin and Petryna, Yuri and Schnellenbach-Held, Martina and Lowke, Dirk and Wessels, Henning and Lenzen, Armin and Zabel, Volkmar and K{\"o}nke, Carsten and Claßen, Martin and Hegger, Josef}, title = {Neuartige Konzepte f{\"u}r die Zustands{\"u}berwachung und -analyse von Br{\"u}ckenbauwerken - Einblicke in das Forschungsvorhaben SPP100+}, volume = {99}, journal = {Bauingenieur}, number = {10}, doi = {10.37544/0005-6650-2024-10-63}, pages = {327 -- 338}, year = {2024}, abstract = {Die Br{\"u}ckeninfrastruktur in Deutschland und Europa steht aufgrund steigender Verkehrslasten und alternder Bauwerke vor erheblichen Herausforderungen. Das DFG-Schwerpunktprogramm 2388 „Hundert plus - Verl{\"a}ngerung der Lebensdauer komplexer Baustrukturen durch intelligente Digitalisierung" (SPP100+) strebt an, durch digitale Innovationen und pr{\"a}diktive Instandhaltungsstrategien die Nutzungsdauer bestehender Br{\"u}ckenbauwerke zu verl{\"a}ngern. Der vorliegende Beitrag fokussiert sich auf das SPP100+ zugeh{\"o}rige Cluster „Monitoring und Simulation", das sieben Teilprojekte umfasst. Die Projekte entwickeln fortschrittliche Methoden zur {\"U}berwachung und Zustandsbewertung von Br{\"u}cken mittels Digitaler Zwillinge, hochaufl{\"o}sender Sensortechnik und numerischer Simulationen. Innovative Ans{\"a}tze wie nichtlineare Modellanpassungen, stochastische Methoden und k{\"u}nstliche Intelligenz erm{\"o}glichen eine pr{\"a}zise und fr{\"u}hzeitige Identifizierung potenzieller Sch{\"a}den. Die Kombination aus kontinuierlichem Bauwerksmonitoring und effizienter Datenauswertung ist entscheidend f{\"u}r die langfristige Sicherheit und Langlebigkeit bestehender Br{\"u}cken und tr{\"a}gt dar{\"u}ber hinaus zur Ressourcenschonung bei.}, language = {de} } @article{GoebelHuynhCheginietal.2025, author = {G{\"o}bel, Fritz and Huynh, Ngoc Mai Monica and Chegini, Fatemeh and Pavarino, Luca and Weiser, Martin and Scacchi, Simone and Anzt, Hartwig}, title = {A BDDC Preconditioner for the Cardiac EMI Model in three Dimensions}, journal = {SIAM J. Sci. Comput.}, arxiv = {http://arxiv.org/abs/2502.07722}, year = {2025}, abstract = {We analyze a Balancing Domain Decomposition by Constraints (BDDC) preconditioner for the solution of three dimensional composite Discontinuous Galerkin discretizations of reaction-diffusion systems of ordinary and partial differential equations arising in cardiac cell-by-cell models like the Extracellular space, Membrane and Intracellular space (EMI) Model. These microscopic models are essential for the understanding of events in aging and structurally diseased hearts which macroscopic models relying on homogenized descriptions of the cardiac tissue, like Monodomain and Bidomain models, fail to adequately represent. The modeling of each individual cardiac cell results in discontinuous global solutions across cell boundaries, requiring the careful construction of dual and primal spaces for the BDDC preconditioner. We provide a scalable condition number bound for the precondition operator and validate the theoretical results with extensive numerical experiments.}, language = {en} } @article{BetzBinkowskiFischbachetal.2025, author = {Betz, Fridtjof and Binkowski, Felix and Fischbach, Jan David and Feldman, Nick and Zschiedrich, Lin and Rockstuhl, Carsten and Koenderink, A. Femius and Burger, Sven}, title = {Uncovering hidden resonances in non-Hermitian systems with scattering thresholds}, volume = {19}, journal = {Laser Photonics Rev.}, arxiv = {http://arxiv.org/abs/2503.03549}, doi = {10.1002/lpor.202500811}, pages = {e00811}, year = {2025}, language = {en} } @misc{BetzBinkowskiFischbachetal.2025, author = {Betz, Fridtjof and Binkowski, Felix and Fischbach, Jan David and Feldman, Nick and Rockstuhl, Carsten and Koenderink, A. Femius and Burger, Sven}, title = {Source code and simulation results: Hidden resonances in non-Hermitian systems with scattering thresholds}, journal = {Zenodo}, doi = {10.5281/zenodo.14651612}, pages = {doi: 10.5281/zenodo.14651612}, year = {2025}, language = {en} } @article{MukherjeeBurgerSiefkeetal.2025, author = {Mukherjee, Deshabrato and Burger, Sven and Siefke, Thomas and Gour, Jeetendra and Bodermann, Bernd and Petrik, Peter}, title = {Spectroscopic Ellipsometry of Plasmonic Gratings─Ideal Parameters for Sensing and Subpicometer Measurement Uncertainty}, volume = {10}, journal = {ACS Omega}, number = {14}, doi = {10.1021/acsomega.5c00951}, pages = {14466 -- 14473}, year = {2025}, language = {en} }