Temperature dependence of energy and entropy of formation of self-interstitials in Cu

The vibrational contribution to energy of formation of self-interstitials in fcc metals is investigated with the use of the Green's-function method. The vibrational contributions to the energy, entropy, and free energy of formation of 〈100〉-split interstitials have been calculated for the case of copper so as to discuss their temperature dependence. The vibrational contribution to the formation energy at low temperatures is {~}0.045 eV. The variation in formation entropy at low temperatures is found to be more pronounced.