The parameter dependence of vacancy and self-interstitial formation energies has been studied with an analytic nearest-neighbor atomistic model based on the embedded-atom method. The model was designed for fcc copper, but the results should not depend on either the structure or the element. Exponentially decreasing functions were used for both the electron density function and the two-body interaction. Energies were dependent on the cutoff procedure for these functions between first and second neighbors, but the conclusions indicate trends and are quite general. Defect energies (vacancy and self-interstitial) were found to have negligible dependence on the cohesive energy, vary only slightly with the bulk modulus, but to be linearly proportional to the average shear modulus. Defect energies were insensitive to variations in the exponent parameters if their average was held constant and thus to whether the two-body potential was attractive or repulsive. Vacancy energies decreased while interstitial energies increased with an increase in the average of the exponent parameters.

• Received 19 October 1987

DOI:https://doi.org/10.1103/PhysRevB.37.6121