Ensemble density functional theory with spherically symmetric densities

The spherical ensemble theory of excited states is developed. The Hohenberg-Kohn theorems are extended to ensembles with spherically symmetric densities via constrained search, and spherical ensemble Kohn-Sham-like equations are derived. The spherical ensemble theory makes it possible to apply a different partition of the energy functional. The spherical Hartree expression is generalized to ensembles. An exactly soluble model of a harmonic two-electron molecule is analyzed.