Static IR and Raman calculations were performed with a setup analogous to the AIMD-based ones: The frequencies were obtained via normal-mode analysis using the FHI-aims package with the same settings as employed in the AIMD runs. After tightly relaxing the AA' structure, 6N structures were generated from the optimized AA' structure (1 × 1 × 2 supercell) by shifting one of the N atoms by 0.001 Å in either ±x, ±y or ±z direction, respectively. The forces were computed for each of the 6N structures and the elements of the Hessian matrix were evaluated numerically via a central finite difference approach. The Berry phase dipole moments and DFPT polarizabilities for the 6N structures were computed with CP2K using again the same settings as for the AIMD snapshots. AIMD trajectories, input and output files of all calculations, and the raw spectral data are available in the Zenodo database.