Although, undeniably the Hartree-Fock Slater determinant has the lowest energy among all Slater determinants, we now know that the Kohn-Sham determinant can at least match, if not beat that (record), since it is "energy optimal" in a similar sense: In the Hartree-Fock optimization, we use the full interacting N-electron Hamiltonian, H and then seek the lowest energy Slater determinant as the best approximate ground state. For the Kohn-Sham orbitals, we may perform an equivalent, but reverse Rayleigh-Ritz optimization: Let us assume that the ground state Ψ of the physical N-electron, interacting system is somehow known (and fixed). Then, we consider all N-electron effective, noninteracting Hamiltonians, H v , with a local potential v(r). The ground-state wave function and energy of each H v are Φ v and E v , respectively.