Structure-Factor Approach to Migration Energy of Interstitials

Abstract

Many lattice defects migrate by processes which involve cooperative motion of a number of interacting atoms on a nearly equal basis, e.g., interstitialcies, crowdions, and dislocations. In particular, migration of the interstitialcy involves only small atomic displacements and electronic redistributions, so it seems likely that its motion energy will be sensitive to the structural configuration around the defect. For this reason, we have applied the pseudopotential formulation of Harrison, which directly includes the effects of structure, to an investigation of interstitial energy differences. Our application has been to the energy difference between body-centered and [100] split interstitials in fcc metals. The numerical results compare reasonably well with earlier calculations employing different force laws, the energy difference in Al being 0.3-0.4 eV.