The atomic rates for H and He-like ions are accurate for densities up to
cm
by taking into account the effects of 3-body
recombination and lowering of the continuum ([Bautista et al. 1998],
[Bautista et al. 1999]). However, these effects are not treated for
other species which reduce the accuracy of the model results for these
ions at high density. The density for which
these effects become important for a given ion increases rapidly with effective charge of
the ion, starting at about
cm
for z=1 and at about
cm
for z=8. At low densities numerical errors can occur;
the user is urged to read chapter 6.