The structure and properties of vacancy loops and stacking-fault tetrahedra were studied by means of computer simulation, using a long-range pair interatomic potential derived from generalized pseudopotential theory and a many-body potential of Finnis-Sinclair type. The results which were obtained using the differing potentials were qualitatively different. Thus, for the long-range pair interatomic potential, significant atomic relaxation was observed for all defects. Triangular vacancy platelets relaxed into regular stacking-fault tetrahedra, and small hexagonal clusters formed Frank loops. Meanwhile, large hexagonal clusters (which contained more than 37 vacancies) could dissociate into 6 truncated stacking-fault tetrahedra with a side that was equal to the <110> side of the hexagon. Similar features were observed following the relaxation of circular loops. In the case of the many-body potential, none of the hexagonal, circular or triangular planar vacancy platelets relaxed into a vacancy loop or stacking-fault tetrahedron, but instead remained as almost unrelaxed so-called holes with a relative stability which was weakly dependent upon the shape.

Vacancy Loops and Stacking-Fault Tetrahedra in Copper I. Structure and Properties Studied by Pair and Many-Body Potentials. J.N.Osetsky, A.Serra, M.Victoria, S.I.Golubov, V.Priego: Philosophical Magazine A, 1999, 79[9], 2259-83