BQCD - Berlin quantum chromodynamics program
Yoshifumi Nakamura, Hinnerk Stüben
TL;DR
BQCD provides an open-source Hybrid Monte Carlo platform for simulating lattice QCD with dynamical Wilson fermions across 2 and 2+1 flavors. It combines Hasenbusch preconditioning, RHMC, and a multi-time-scale integrator to improve sampling efficiency, together with a suite of solver and preconditioning techniques to accelerate fermion matrix inversions. The implementation emphasizes portability and performance on HPC architectures via Fortran, MPI/OpenMP, mixed-precision solvers, and robust data formats, with comprehensive measurements of gluonic and fermionic observables. The work has broad impact by enabling reproducible, high-performance lattice QCD studies and serving as a foundational codebase for collaborations and hardware porting efforts.
Abstract
We publish BQCD as free software under the GNU General Public License. BQCD is a Hybrid Monte-Carlo program that simulates lattice QCD with dynamical Wilson fermions. It is one of the main production programs of the QCDSF collaboration. The program can simulate 2 and 2 + 1 fermion flavours with pure, clover improved, and stout smeared fat link Wilson fermions as well as standard plaquette, and an improved (rectangle) gauge action. The single flavour is simulated with the Rational Hybrid Monte-Carlo algorithm.