Mainz Materials Simulation Days 2017 June 12, 2017 - June 14, 2017 CECAM-DE-SMSM Max Planck Institute for Polymer Research Mainz, Germany Friederike Schmid Institute of Physics, Johannes Gutenberg University, Mainz, Germany Burkhard Dünweg Max Planck Institute for Polymer Research, Mainz, Germany Kostas Daoulas Max Planck Institute for Polymer Research, Mainz, Germany Kurt Kremer Max Planck Institute for Polymer Research, Mainz, Germany Astrid Chase Institute of Physics, Johannes Gutenberg University, Mainz, Germany 1 Description Please consult also the special page http://www.mpip-mainz.mpg.de/4874119/MMSD2017 for this event! The Mainz Materials Simulation Days are by now an established series of biennial meetings organized by the Max Planck Institute for Polymer Research and the University of Mainz in Germany. As a topic for the 2017 meeting, we have chosen "Hybrid simulations involving particles and field theory", where we have in mind systems with hydrodynamic and/or electrostatic interactions, but also polymer systems simulated by a hybrid algorithm involving chains of particles and a Mean Field background. We hope that bringing these complementary approaches together will result in inspiring new ideas. 2 Program Day 1 - Monday June 12, 2017 Startup • 10:00 to 11:00 - Registration • 11:00 to 11:10 - Welcome Oral Session I (Maria Lukacova, Rudolf Hilfer) • 11:10 to 11:50 - Presentation • 11:50 to 12:10 - Presentation Lunch • 12:10 to 13:30 - Lunch Oral Session II (Marcus Mueller, Stephan Baeurle, Venkat Ganesan) • 13:30 to 14:10 - Presentation • 14:10 to 14:50 - Presentation • 14:50 to 15:30 - Presentation Poster session I • 15:30 to 17:00 - Poster Session Oral session III (Doros Theodorou, Hsiao-Ping Hsu) • 17:00 to 17:40 - Presentation • 17:40 to 18:00 - Presentation Conference Dinner at Bonnheimer Hof, Hackenheim (Bus Transfer) • 18:30 to 22:00 - Social Dinner Day 2 - Tuesday June 13, 2017 Oral Session IV (Kirsten Martens, Marco Ellero, Andreas Troester) • 9:00 to 9:40 - Presentation • 9:40 to 10:20 - Presentation • 10:20 to 10:40 - Presentation Coffee • 10:40 to 11:10 - Coffee Break Oral Session V (Robin Ball, Mehmet Sayer) • 11:10 to 11:50 – Presentation • 11:50 to 12:10 - Presentation Lunch • 12:10 to 13:30 - Lunch Oral Session VI (Jens Harting, Roland Winkler, Tapan Chandra Adhyapak, Fabian Kössel) • 13:30 to 14:10 - Presentation • 14:10 to 14:50 - Presentation • 14:50 to 15:10 - Presentation • 15:10 to 15:30 - Presentation Coffee break • 15:30 to 16:00 - Coffee Break Oral Session VII (Monica Olvera de la Cruz, Daniel Vega) • 16:00 to 16:40 - Presentation • 16:40 to 17:00 - Presentation Poster Session II (With Drinks and Snacks) • 17:00 to 19:00 - Poster Session Day 3 - Wednesday June 14, 2017 Oral Session VII (Tony Maggs, Christian Holm, Omar Valsson) • 9:00 to 9:40 - Presentation • 9:40 to 10:20 - Presentation • 10:20 to 10:40 - Presentation Coffee • 10:40 to 11:10 - Coffee Break Oral Session IX (Christoph Scherer, Agur Sevink) • 11:10 to 11:30 – Presentation • 11:30 to 12:10 - Presentation Famous Last Words • 12:10 to 12:30 - Closing Word Lunch • 12:30 to 14:00 - Lunch 3 Abstracts Invited Talks How to bridge large scale differences? Maria Lukacova [1], Burkhard Dünweg [2], Nehzat Emamy [1], Stefanie Stalter [1], Paul Strasser 1], Nikita Tretyakov [2], Peter Virnau [1], Leonid Yelash [1], [1] Institute of Mathematics, University of Mainz; [2] MPI Polymer Research Mainz, Germany In this contribution we present two examples of modeling multiscale problems such as the polymer- solvent mixtures and colloid-polymer systems. Of course, the most accurate description of such complex soft matter systems would be obtained by the molecular dynamics (MD). However, such microscale model is computationally inefficient if large scale regions in space and time need to be simulated. We present two approaches how to overcome this restriction and obtain practically tractable simulation techniques to bridge macroscopic and microscopic models. First, we present a new reduced-order hybrid multiscale method that is based on the combination of the discontinuous Galerkin method and molecular dynamics simulations, see [1]. We follow here the framework of the heterogeneous multiscale method that makes use of the scale separation into macro and micro- levels. On the macro-level the governing equations of the incompressible flow are the continuity and momentum equations. The equations are solved using a high-order accurate discontinuous Galerkin method. The missing information on the macro-level is represented by the unknown stress tensor that is evaluated by means of the molecular dynamics simulations on the micro-level. The data obtained from the MD simulations underlie relatively large stochastic errors that can be controlled by means of the least-square approximation. Moreover, in order to reduce a large number of computationally expensive MD runs we use the reduced order approach. We split the computations into an off-line phase of expensive training and an on-line phase of fast multiple queries. In the training phase we use the Greedy sampling algorithm as a model reduction technique to replace the unknown nonlinear stress-strain function by a reliable low-dimensional approximation. Numerical experiments confirm the robustness of our newly developed hybrid MD- dG method. In the second part of our talk we present a new second order energy dissipative finite volume-finite difference scheme to treat macroscopic equations aiming at the modeling of the dynamics of complex polymer-solvent mixtures. This model consists of the Cahn–Hilliard equation for diffuse interface phase fields and the Oldroyd-B equations for the hydrodynamics of the polymeric mixture, cf. [2]. A complementary approach to study the same physical system is realized by simulations of a microscopic model based on a hybrid Lattice Boltzmann-MD scheme. These latter simulations provide initial conditions for the numerical solution of the macroscopic equations. Our ultimate goal is the systematic coarse-graining of simulation models by means of optimal control of well-chosen observables, such as structure factors. The present research has been supported by the German Science Foundation under the grant TRR 146 “Multiscale Simulation Methods for Soft Matter Systems.” [1] N. Emamy, M. Lukacova-Medvidova, S. Stalter, P. Virnau, and L. Yelash Reduced-order hybrid multiscale method combining the Molecular Dynamics and the Discontinuous-Galerkin method, 2017, submitted. [2] M. Lukacova-Medvidova, B. Dünweg, P. Strasser, and N. Tretyakov: Energy-stable numerical schemes for multiscale simulations of polymer-solvent mixtures, to appear in Mathematical Analysis of Continuum Mechanics and Industrial Applications II, Proceedings of the International Conference CoMFoS16, Springer Singapore, 2017. Process directed self-assembly of copolymers Marcus Müller [1] [1] Georg-August University, Göttingen, Germany Process-directed self-assembly of block copolymers refers to rapid thermodynamic processes that reproducibly direct the kinetics of structure formation from a starting, unstable state into a selected, metastable mesostructure. We investigate the kinetics of self-assembly of linear block copolymers after different rapid changes of thermodynamic control parameters (e.g., photochemical transformations [1], stretching [2], or pressure changes [3]). These thermodynamic processes convert an initial, equilibrium mesophase of the copolymer material into a well-defined but unstable, starting state. The spontaneous structure formation that ensues from this unstable state becomes trapped in a metastable mesostructure, and we systematically explore, which metastable mesostructures can be fabricated. Strategies and challenges for studying process-directed self- assembly by particle-based simulations and self-consistent field theory are discussed and the role of non-equilibrium chain conformations and the diffusive dynamics is highlighted. [1] Process-accessible states of copolymers D.W. Sun and M. Müller, Phys. Rev. Lett. 118, 067801 (2017) [2] Alignment of copolymer morphology by planar step elongation during spinodal self-assembly M. Müller and J. Tang, Phys. Rev. Lett. 115, 228301 (2015) [3] Directing the self-assembly of block copolymers into a metastable complex network phase via a deep and rapid quench M. Müller and D.W. Sun, Phys. Rev. Lett. 111, 267801 (2013) Exploring the Performance Enhancement Potential of the Tapering Technology for Blockcopolymer Solar Cells using a Multiscale Solar-cell Algorithm Stephan Baeurle [1], Anton Pershin [1], Sergii Donets [1] [1] Institute of Physical and Theoretical Chemistry, University of Regensburg, D-93040 Regensburg, Germany Tapered block copolymers offer an exciting opportunity to tailor the interfacial region between different components while conserving the phase-separated mesoscale structure. In this presentation, we explore their usefulness for optimizing the photovoltaic performance of polymer bulk heterojunctions. This is achieved by applying a recently developed multiscale solar-cell algorithm [1,2,3], to investigate the effect of random tapering at the chemical junctions between the electron-donor- (D) and electron-acceptor- (A) blocks on the photovoltaic properties of various lamellar-like polyfluorene-based block-copolymer systems. Our simulation results [2] reveal that introducing a tapered middle block with optimal length leads to a significant increase of the exciton dissociation efficiency and deteriorates the charge transport efficiency