Using our GA structure-prediction protocol, we generated four TiOF 2 4×4×4 supercells for validation against our experimental PDF and 19 F NMR data. For each supercell, we initially relaxed atomic positions and cell volume (fixed cell shape) in VASP, using the parameters described above and a 2 × 2 × 2 Monkhorst-Pack k-point grid. For input structures for 19 F NMR spectra calculations, we then performed a full optimisation (atomic positions, cell volume, and cell shape) using CP2K , using the PBE GGA exchange-correlation functional and the DFT-D3 dispersion-correction method of Grimme et al. , which corrects for the overestimation of bondlengths and cell volumes found for typical PBE calculations . The CP2K calculations used Goedecker-Teter-Hutter (GTH) pseudopotentials and TZVP Gaussian basis sets (MOLOPT library), with charge density plane-wave expansion energy cutoff of 720 Ry.