Proton diffusion in lutetium

The configurational energy of the proton is investigated in the lutetium matrix. The bare ion is represented by a model potential and the modified Hartree dielectric function is used for the screening due to conduction electrons. The octahedral (O) position is found to be the most probable position for the proton and the activation energy is found to be in good agreement with the experimental value for an effective charge on the proton of 0.23e. It is concluded that the proton diffuses by the hopping process and that the O-O, O-T(tetrahedral)-O and O-T-T-O paths are equally probable for the diffusion. The configurational energy obtained by varying the c/a ratio and the core radius, and that for the dilated lattice, are also calculated and discussed. (Auth.)