An ab initio first-principles study was made of defect-induced self-diffusion in Na. Calculations of the migration energy and of the phonon spectrum in the presence of a vacancy confirmed the hypotheses of a low barrier and a high entropy of migration. Results on the relative contributions made by various defect mechanisms to the Na self-diffusion coefficient, obtained by direct simulation, indicated that the interstitial made a significant contribution to self-diffusion at temperatures close to the melting point; thus providing a possible explanation for a bend in the Arrhenius plot at high temperatures.

Self-Diffusion in Sodium via ab initio Molecular Dynamics. E.Smargiassi: Physical Review B, 2002, 65[1], 012301 (4pp)