  We consider the secular behavior of shell-model configuration (partial)
densities. When configuration densities are characterized by their moments, one
often finds large third moments, which can make suitable parameterization of
the secular behavior problematic. We review several parameterizations or
models, and consider in depth three specific models: Cornish-Fisher, binomial,
and modified Breit-Wigner distributions. Of these three the modified
Breit-Wigner provides the best secular approximation to exact numerical
configuration densities computed via full diagonalization from realistic
interactions.
