Accessibility and Sustainability for the tmLQCD software suite

• Applicant: Dr. Bartosz Kostrzewa
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 528533525

Lattice Quantum Chromodynamics is the only systematically improvable means of studying the strong interaction from first principles at low energy, for which it relies on complex software frameworks and uses a substantial fraction of the available computing time on the largest supercomputers in the world. The tmLQCD software suite is the main production code of the Extended Twisted Mass Collaboration (ETMC) and the Twisted Wilson @ EXTreme conditions (TWEXT) collaboration. Amongst other functionalities, it is used to generate so-called ensembles of gauge configurations which are the basis of the physics research programs of these collaborations. In this project, we propose to make substantial improvements to the usability, impact and quality assurance of tmLQCD through software engineering activities which will also serve to encourage further development and open tmLQCD up to usage beyond the work of the ETMC and TWEXT collaborations. To enable the wider community to make use of tmLQCD's library-based support for state of the art CPU-based as well as GPU-accelerated supercomputers and algorithms, we propose a rigorous cleanup of the tmLQCD source code, substantial extensions of the continuous integration pipeline and a refinement and elaboration of the available documentation, including the provision and maintenance of a number of example input files for many different physical situations, machines and algorithms. Similarly, we aim to provide and maintain tmLQCD build recipes for the main supercomputing platforms in Europe and beyond, thereby making it easier for potential new users to employ tmLQCD without expert guidance. Beyond the extension of unit and integration tests, we aim to extend the meta-data that tmLQCD writes into output and log files, thereby not only improving provenance tracking in the sense of the FAIR principles but also aiding in defect tracing and resolution. In the same vein, we propose to modify the random number generator in tmLQCD to enable much better reproducibility, making it much easier to check calculations in case of irregularities or software defects. In order to continue and improve the sharing of gauge configurations with the entire community, we will adapt to any developments stemming from the rejuvenation of the International Lattice Data Grid. A step-by-step contributors guide, a completely revised build system, the support of a research software engineer in managing tmLQCD's development flow on github as well as the introduction of an official citation policy are aimed at encouraging non-core developers to contribute. Finally, in order to highlight the importance of this software engineering work in the lattice QCD community and beyond, we aim to present our work and tmLQCD in general at various supercomputing and lattice QCD conferences and workshops.

• DFG Programme: Research Grants
• International Connection: Cyprus, Italy
• Co-Investigators: Professor Dr. Stefan Krieg; Professor Dr. Carsten Urbach
• Cooperation Partners: Dr. Simone Bacchio; Dr. Francesco Sanfilippo