Simple models for shell-model configuration densities

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 (asymmetries), which make suitable parametrization of the secular behavior problematic. We review several parameterizations or models and compare to exact numerical configuration densities. We propose a modified Breit-Wigner form which provides a better secular approximation, for large asymmetries, compared to models based on Gaussian forms.