  The effect of the lattice relaxation at vacancy clusters and
interstitial-type dislocation loops on the lifetime of positrons in Zn has been
studied. Defective relaxed structures have been generated for the lifetime
calculations by using a many-body potential for Zn. From the results, it is
inferred that the effect of the atomic relaxation is mainly significant for
small vacancy clusters. The lifetime associated with interstitial-type loops is
very sensitive to the loop structure and its surroundings. Previous
experimental results are compared with the theoretical calculations.
