Comments on Correlation Calculations in Anisotropic Diffusion

A method is proposed for calculating correlations for impurity diffusion. The method can be applied to any lattice, isotropic or anisotropic, and permits all symmetrically inequivalent dissociative jump frequencies to be uniquely specified without adding to the complexity of the calculation. The method is compared with other methods for the face-certered-cubic, body-centered- tetragonal, and hexagonal-ciose-packed lattices. An accurate empirical representation of previously calculated self-diffusion correlations is given for the bct and hcp lattices. (H.D.R.)