  Large-scale calculations of atomic structures and radiative properties have
been carried out for singly, doubly- and trebly ionized cerium. For this
purpose, the purely relativistic multiconfiguration Dirac-Hartree-Fock (MCDHF)
method was used, taking into account the effects of valence-valence and
core-valence electronic correlations in detail. The results obtained were then
used to calculate the expansion opacities characterizing the kilonovae observed
as a result of neutron star mergers. Comparisons with previously published
experimental and theoretical studies have shown that the results presented in
this work are the most complete currently available, in terms of quantity and
quality, concerning the atomic data and monochromatic opacities for Ce II, Ce
III and Ce IV ions.
