A Car-Parrinello-type linear-scaling scheme which used the density as the basic variable, was used to simulate the finite-temperature behaviour of point defects in sodium. It was shown that the method gave good results when applied to simple metals, using however only a fraction of the computational resources required by more conventional schemes. Results for the (fully anharmonic) free energies and for the structural properties of point defects were obtained, showing that the interstitial was more common than had previously been thought, and might even be the predominant defect at temperatures close to the melting point. Preliminary results on the relative contributions of the various defect mechanisms to the sodium self-diffusion coefficient obtained via direct simulation were considered, with particular reference to long-standing problem of self-diffusion in body-centered cubic metals.

Defect Properties and Diffusion in Sodium using ab initio Molecular Dynamics. Smargiassi, E.: Computational Materials Science, 2001, 20[3-4], 416-22