ZQC-SABRE Simulator: graphical software for symmetry-reduced simulations of SABRE field dependence and ZULF NMR spectra

ZQC-SABRE Simulator is a Python desktop application for numerical simulations of Signal Amplification by Reversible Exchange (SABRE) under zero- and ultralow-field (ZULF) conditions. The software provides a graphical user interface to the symmetry-reduced Liouville-space framework described in: D. Markelov, A. Snadin, A. Kiryutin, D. Barskiy, and A. Yurkovskaya, “Scalable modeling of multi-spin ensembles in SABRE hyperpolarization: a symmetry-based framework for zero and ultralow fields,” Magnetic Resonance 7, 53–79 (2026). DOI: 10.5194/mr-7-53-2026. The numerical backend implements the ZQC-reduced SABRE master-equation, including coherent spin evolution, relaxation, and reversible substrate exchange. The graphical interface allows these calculations to be configured and performed without direct modification of the numerical source code. The program supports two main simulation modes: Magnetic-field dependence of SABRE hyperpolarizationCalculation of substrate polarization and user-defined spin orders over a user-defined range of magnetic fields. ZULF NMR spectrum simulationSABRE polarization at a selected magnetic field followed by free evolution at a near-zero detection field, calculation of the ZULF free-induction decay (FID), and Fourier transformation to obtain the frequency-domain spectrum. Supported spin-1/2 nuclei are: ¹H, ¹³C, ¹⁵N, ¹⁹F, ²⁹Si, ³¹P, and ⁷⁷Se. Distribution contents The software distribution contains: app.py — Tkinter/Matplotlib graphical user interface; zqc_sabre_core.py — ZQC-SABRE numerical backend; requirements.txt — required Python packages; run_windows.bat — Windows launcher; README.md — installation and quick-start information; USER_GUIDE.pdf — illustrated step-by-step user manual describing every GUI panel and the recommended simulation workflow.