Subspace theory with spherically symmetric densities.

Recently, it has been proved that a set of spherically symmetric non-degenerate densities determines uniquely the Coulomb external potential. This theory is now extended to degenerate states. Euler equations and Kohn–Sham equations are derived and a novel form of the virial theorem is presented. It is emphasized that degenerate states of atoms can be rigorously treated as spherically symmetric when a subspace density is used with equal weighting factors. [ABSTRACT FROM AUTHOR]