In a previous work it was shown by computer simulation of point-defect migration that the recombination cross section Ziv, is substantially smaller than normally quoted in literature. In the present work we use a different type of computer program that, unlike the former program, includes the actual recombination event. This makes it possible to cover the range of vacancy concentrations from very high values down to 10−6 and to include the case where interstitials and vacancies are equally mobile. We are therefore in a position to establish the dependence of Ziv, on the various relevant parameters. The relation between the present atomistic approach and the alternative continuum approach is discussed.