Andreas Reiter

The parallel multi-physics phase-field framework PACE3D

Abstract The phase-field method has been established for the numerical investigation of various microstructure evolution processes. The accurate description of these complex processes requires large domains and suitable models, allowing to couple several physical fields in statistical representative volume elements. To simplify the implementation of new models and to reduce the simulation run time, different frameworks have been developed. In this work, the parallel multi-physics phase-field framework Pace3D is introduced. The general structure of the solver, its modules and the parallelization are described. For increasing the performance of the implemented phase-field models, various optimization techniques are outlined. To efficiently store the simulation results, different data formats and parallel writing mechanisms are presented. The performance of an optimized implementation for a specific phase-field model is analyzed on a single core, showing a good peak performance. For a single node, the memory bandwidth is analyzed and ruled out as possible bottleneck. In addition, a proper weak scaling behavior is demonstrated on the three supercomputers ForHLR I, ForHLR II and Hazel Hen, for up to 96 100 cores.

Electric-field-induced lamellar to hexagonally perforated lamellar transition in diblock copolymer thin films: kinetic pathways

Symmetric block-copolymers, hitherto, are well known to evolve into parallel, perpendicular and mixed lamellar morphologies under the concomitant influence of an electric field and substrate affinity. In the present work, we show that an additional imposed confinement can effectuate a novel parallel lamellar to hexagonally perforated lamellar (HPL) transition in monolayer and bilayer films. Three dimensional numerical studies are performed using the Ohta-Kawasaki functional, complemented with an exact solution of Maxwells equation. HPL is shown to stabilize at large substrate affinity in a narrow region of the phase diagram between parallel and perpendicular lamellar transitions in ultra-thin films. Additionally, we also identify perforated lamellae as intermediate structures during parallel-to-perpendicular lamellar transition. A systematic analysis using Minkowski functionals yields deeper insights into the associated kinetic pathways.