PROPERTIES OF MONOVACANCIES AND SELF-INTERSTITIALS IN BCC LI - AN AB-INITIO PSEUDOPOTENTIAL STUDY

The formation energy E1V(F) and the structural relaxation for a vacanc y in bcc Li are calculated within the framework of the local-density a pproximation and the ab initio pseudopotential method for super-cells, thereby correcting a small error in the pseudopotential used in forme r calculations. The calculated value of E1V(F) = 0.54 eV is nearly ide ntical to the activation energy for self-diffusion, suggesting an extr aordinarily small vacancy-migration energy or a nonvacancy mechanism o f self-diffusion. The results for self-interstitials exclude an inters titialcy mechanism. A local relaxation volume of -0.51 atomic volumes was found for the vacancy.