DENSITY-FUNCTIONAL THEORY FOR EXCITED-STATES

A subspace theory of the density functional for excited states is show n to give the density of states. Useful inequalities connecting the el ectronic energies of atoms and molecules are presented. A metric is de fined for the set of M-dimensional subspaces of a Hilbert space to giv e a theorem on the convergence of subspaces. For central potentials of non-interacting systems the density due to the orbitals with certain defined angular momenta determine uniquely the ground state and the po tential.