Proton dynamics in high-pressure ice-VII from density functional theory

Using a density functional theory based approach, we explore the symmetrization and proton dynamics in ice-VII, for which recent high-pressure NMR experiments indicate significant proton dynamics in the pressure-range of $20--95\phantom{\rule{4pt}{0ex}}\mathrm{GPa}$. We directly sample the potential seen by the proton and find a continuous transition from double- to single-well character over the pressure range of 2 to 130 GPa accompanied by proton dynamics, in agreement with the NMR experiments.