Wave-functions and energy spectra were calculated for an isolated proton in a crystalline material. The ground-state wave-function was strongly localized at the minimum energy positions near to the bond centers. It was noted that so-called M-sites, which had almost the minimum energy, had only a small probability of occupation. The lower-energy excited states were also well-localized. Overall, it was deduced that quantum effects were unimportant with regard to H diffusion through the host.

C.Pennetta: Europhysics Letters, 1991, 14[7], 683-8