The 19 F magnetic-shielding tensors for these geometryoptimised TiOF 2 4 × 4 × 4 supercells were calculated using the GIPAW approach within VASP , using the PBE GGA exchange-correlation functional with a 550 eV plane-wave cutoff and a 2×2×2 Monkhorst-Pack k-point grid. The simulated 19 F MAS NMR spectra were constructed from the DFT-calculated 19 F magnetic shielding data using the procedure described in Ref. . For each fluorine atom, a MAS NMR spectrum was simulated, given the relevant experimental values of spin rate (64 kHz) and the magnetic field (7 T). The full MAS NMR spectrum for a given structural model was then obtained by summing the spectra for all the constituent fluorine atoms. The simulated 19 F NMR spectra were computed using the fpNMR package .