INTERACTION ENERGIES OF POINT-DEFECTS IN METALS - NONLOCAL EFFECT BEYOND THE LSDA

We examine the non-local effect (NLE) beyond the LSDA for defect inter actions, such as I-I(I = 3d and 4sp impurities) and V-I (V = vacancy) interactions, in metals (Al, Ni, Cu). The calculations are based on th e generalized-gradient approximation proposed by Perdew and Wang. We f ind that the NLE is very small for I-I interations, while it becomes l arge for V-I interactions and depends on the host; the NLE is attracti ve for V-I interactions in Al, almost zero for V-I in Ni, and repulsiv e for V-I in Cu. The micromechanism of this host dependence is discuss ed.