The overall correlation with the simple LFSE formula can be explained
by the fact that the effective Kohn–Sham operators defining
the whole orbital scheme are modulated by the occupation of
the d-type sequence. Moreover, it seems that the leverage stays
in the two-electron terms (Coulomb and exchange effects) but
the dependence on the electron count is parallel to those marked
in the one-electron LFSE-type formula.