Proper treatment of symmetries and excited states in a computationally tractable kohn-sham method

A new Kohn-Sham (KS) formalism, the symmetrized generalized adiabatic connection KS formalism, is introduced. It is applicable to ground as well as excited states and does not suffer from the symmetry problems of the standard KS approach. In all cases a totally symmetric, non-spin-polarized KS Hamiltonian operator arises. Complete electronic spectra, including multiplet splittings, Rydberg series, and x-ray and Auger data can be described. Results for the carbon atom and the carbon monoxide molecule are presented.