  Ensemble density functional theory extends the usual Kohn-Sham machinery to
quantum state ensembles involving ground- and excited states. Recent work by
the authors [Phys. Rev. Lett. 119, 243001 (2017); 123, 016401 (2019)] has shown
that both the Hartree-exchange and correlation energies can attain unusual
features in ensembles. Density-driven(DD) correlations -- which account for the
fact that pure-state densities in Kohn-Sham ensembles do not necessarily
reproduce those of interacting pure states -- are one such feature. Here we
study atoms (specifically $S$--$P$ and $S$--$S$ transitions) and show that the
magnitude and behaviour of DD correlations can vary greatly with the variation
of the orbital angular momentum of the involved states. Such estimations are
obtained through an approximation for DD correlations built from relevant exact
conditions Kohn-Sham inversion, and plausible assumptions for weakly correlated
systems.
