Having established that DFT calculations can accurately obtain the NMR parameters of Ga sites in well-defined molecular structures, we then turned our attention to modelling possible surface species and their associated NMR signatures. On the basis of observations from XANES and fitting of EXAFS, tetra-coordinate sites, containing 3 siloxide ligands and an adjacent neutral donor, that can be either a siloxane bridge (GaLA) or a silanol group (GaBA), were chosen as models (See Figure or SI S6). Note that while tri-coordinate Lewis acid sites are not considered to be present in large concentrations in Ga@SiO2 based on analysis of XAS (vide supra), the NMR parameters of these species were also calculated for reference (vide infra). For GaLA, the calculated δiso/CQ are 142 ppm/39 MHz while the calculated δiso/CQ for GaBA are 137 ppm/42 MHz (Figure , Ga-L distances are summarized in SI S6). The CQ values are comparable to