Distinguishing the Structures of High-Pressure Hydrides with Nuclear Magnetic Resonance Spectroscopy.

The structural characterization of high-pressure hydrides has encountered many difficulties mainly due to the weak X-ray scattering of hydrogen. Herein, we investigate the prospect of detecting the H3S and LaH10 structures with nuclear magnetic resonance (NMR) spectroscopy. Our calculations demonstrate that the different candidate structures of H3S (or LaH10) exhibit significant differences in the electric field gradient (EFG) tensor of the 33S (or 139La) sites, indicating that the NMR spectroscopy can well capture the structural differences, even the small changes in the atomic position, and hence can be used to effectively probe the structures and the phase transitions of H3S and LaH10. Our results clarify the relationship between the structures and the EFG tensor parameters and provide a potential means to detect the structures of high-pressure hydrides.