The total energy surfaces for a positively charged particle, diffusing in a perfect Si crystal, were calculated. Negligible lattice distortion was assumed. Local density functional theory and  ab initio  norm-conserving pseudopotentials were used within a linear response scheme. It was concluded that H+ diffusion involved many different sites; including the bond center. Various migration paths, with entirely different energy barriers, were possible.

C.Pennetta: Solid State Communications, 1989, 69[3], 305-9