Mobility of Interstitial Atoms in a Face-Centered Metal

Calculation of the energies of interstitial atoms in copper have been carried through in some detail using a free-electron model and approximating the repulsion of closed shells with a Born-Mayer potential. Alternate choices of constants in this potential have been employed to explore the extent of the associated uncertainty. Results show that interstitials require an activation energy of about {} ev or less for motion. Applications to various current experiments are pointed out.