A pair potential calculation of vacancy formation and migration energies for aluminium and copper

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Abstract
Vacancy formation and migration energies and enthalpies are computed for aluminium and copper using potential functions derived earlier by fitting to phonon frequencies. Also, the local density correction proposed by Finnis and Sachdev is evaluated for the formation energy in both the metals. The calculated formation and migration enthalpies, 0.84 and 0.65 eV for Al and 1.38 and 0.80 eV for Cu, respectively, are close to the corresponding experimental values. The results are considered in terms of third‐order contributions of the total energy. The third‐order contribution to the formation energy is expected to be of the order of the experimental formation enthalpy in the case of Al but considerable smaller in the case of Cu. On the other hand, the two‐body potential approach almost suffices to explain the experimental figures for the migration enthalpy, since the third‐order terms for the initial and saddle‐point configurations in the migration process largerly cancel each other.