JuRSE Code of the Month - August 2026

Each month we highlight a code from Forschungszentrum Jülich and this month's code is PEPC, developed at the Jülich Supercomputing Centre (JSC).

PEPC
The Pretty Efficient Parallel Coulomb Solver (PEPC) is a publicly available tree code that has been developed at Jülich Supercomputing Centre since the early 2000s. The code is a non-recursive version of the Barnes-Hut algorithm, using a level-by-level approach to both tree construction and traversals.

JuRSE selected highlights
When this code was born the JSC was still called the "Zentralinstitut für Angewandte Mathematik" (ZAM), fusion was only 20 years away (or so), and research software engineering was not a thing. All these changed, and so did this code: over successive PhD theses, postdocs, students, researchers, and collaborators (disclaimer: two of those happen to be part of JuRSE) this multi-physics framework experienced multiple rewrites, structural changes, additions, removals, and hot disputes about its future. It may be a bit weathered, but thanks to its modularity, the code is still in demand. Since late 2025 it has featured in the Helmholtz AI NEOPIC project, and just recently became part of an upcoming EuroHPC Centre of Excellence on plasma physics, injecting fresh 3rd party funding into this decade-old research software. Lessons learned: Putting time and effort into your software gives it a fighting chance; without that investment, success is impossible.

More information
Website: http://www.fz-juelich.de/jsc/pepc
RSD: https://helmholtz.software/software/pepc
Gitlab: https://gitlab.jsc.fz-juelich.de/SLPP/pepc