Figure 5.

(a) Binding energy and (b) migration energy of interstitial clusters in the four GBs as a function of size. In (a), the formation energy of an interstitial in bulk Cu is indicated, as this is a lower bound of the binding energy of interstitials to any boundary (if the binding energy were lower, the interstitials would form spontaneously at the boundary). In (b), the migration energies of interstitials and vacancies in bulk Cu are indicated for comparison.