Best Paper Award at EuroHPC User Days Goes To JSC Team

The JSC experts Rodrigo Bartolomeu, René Halver and Godehard Sutmann received the Best Paper Award today at the EuroHPC User Days 2026 for their submission “Scaling and performance aspects of the P3M method on multiple GPUs“. The three scientists work in the JSC’s Simulation and Data Laboratory Complex Particle Systems. In their award-winning work they developed a library for electrostatic solvers with implementations for different mathematical methods, which is optimized for CPU and GPU architectures.

The computational bottleneck in particle-based simulations

Long-range electrostatic interactions constitute a major computational bottleneck in particle-based simulations, particularly when periodic boundary conditions are employed. Without applying sophisticated methods, such computations have a computational complexity of O(N²), which means that the number of required calculations grows exponentially with the number of particles in the simulation: For 100 particles the number of required calculations is a function of 100²=10,000; for 1000 particles it is already a function of 1,000²=1,000,000.

Mesh-based Ewald methods, such as the particle-particle particle-mesh (P3M) approach, reduce the computational complexity to O(N log N), i.e. for 100 particles the number of calculations is a function of 100*log₁₀(100)=200 instead of 10,000, and for 1,000 particles it is 1,000*log₁₀(1,000)=3,000 instead of 1 million computations. But these methods introduce challenges related to parallel scalability, communication overhead, and efficient utilization of modern heterogeneous architectures, i.e. to how well and efficient they run on a supercomputer. While highly optimized implementations exist in established molecular dynamics packages, these are typically tightly coupled to full simulation frameworks, limiting their flexibility and reuse in emerging HPC applications.

A new library with an efficient parallel solver for heterogeneous platforms

In their paper, Rodrigo and his colleagues present a performance-portable library for electrostatic solvers, providing implementations of both classical Ewald and P3M methods targeting CPU and GPU architectures. The library is designed to enable the efficient execution on multi-GPU systems while maintaining portability across heterogeneous platforms.

They investigate the scaling and performance characteristics of the P3M method, with particular focus on the FFT-based long-range component, which is known to limit scalability: Strong-scaling experiments demonstrate that small problem sizes are dominated by communication overhead, leading to reduced parallel efficiency, whereas larger systems achieve near-ideal scaling over a wide range of GPU counts.

The results highlight the importance of balancing computation and communication in mesh-based electrostatics and demonstrate that portable, decoupled implementations can achieve competitive performance on modern HPC systems. The presented approach facilitates integration into diverse simulation workflows and provides a foundation for further optimization of long-range solvers in exascale computing environments. The authors used three supercomputers for their project: MareNostrum5 at the Barcelona Supercomputing Centre, and JURECA-DC and JUWELS Booster at the JSC. Their work is part of the MultiXscale Centre of Excellence.

The EuroHPC User Days

The EuroHPC User Days are this week the place-to-be for the European HPC community. The event provides supercomputing users in Europe with the chance to explore various topics and enhance their understanding of the opportunities provided by the EuroHPC Joint Undertaking and the support available to users. EuroHPC projects are showcased that have used European HPC, Quantum Computing and AI supercomputing resources to present best practices in the development of these projects, gather feedback from EuroHPC users and engage with potential new users. This year, the event takes place in Dublin, Ireland, organised by the EuroHPC Joint Undertaking, together with the Irish Centre for High-End Computing (ICHEC) and the Department of Further and Higher Education, Research, Innovation and Science of Ireland, under Ireland’s Presidency of the Council of the European Union. Rodrigo Bartolomeu received the award certificate today evening during the Award Session.

More information

News report by EuroHPC JU: https://www.eurohpc-ju.europa.eu/eurohpc-user-days-2026-awards-celebrating-innovative-supercomputing-solutions-todays-challenges-2026-09-23_en

The paper is available under open access:

Contact: Dr. Rodrigo Bartolomeu