Green's-function calculation of entropy of formation of self-interstitials in Cu

The entropy of formation of self-interstitials in fcc metals is determined using a Green's-function technique. The results on the dynamics of self-interstitials in the 100 > dumbbell configuration, discussed in an earlier work, are employed to compute the entropy of formation of this defect in Cu. In addition to the contribution due to local perturbation, the effect of lattice expansion is taken into account. The result for the entropy of formation, $3.42k$, is found to be considerably lower than the two previous cluster calculations based on the Einstein approximation.