First-principles study of self-diffusion in hcp Mg and Zn

Self-diffusion coefficients for hcp Mg and Zn have been calculated from first-principles as a function of temperature, within the generalized gradient and local density approximations. The climbing image nudged elastic band (CI-NEB) method has been used to provide minimum energy pathways and associated saddle point structures. Vibrational properties have been calculated using the direct method to lattice dynamics. A good agreement between our calculated data and available experimental measurements has been obtained. For both Mg and Zn, LDA and GGA results form lower and upper bounds to the experimental data. Calculated results show that diffusion is faster in the basal plane in Mg and along the normal of the basal plane in Zn, in accordance with the available experimental data. Key differences in the diffusion anisotropy of both the metals have been examined in detail.