This procedure can be seen as the Hartree-only version for single-configuration (Kohn-Sham) wave functions of the state-averaged complete-active-space self-consistent-field (SA-CASSCF) method. Its practical disadvantage is that standard SCF routines cannot be used in this context. Indeed, as each Kohn-Sham state generates its own Hartree potential, there is no single ensemble potential from which the minimizing Kohn-Sham orbitals can be determined (by diagonalization). If we want to avoid the use of OEPs, this is essentially the price to pay for constructing ghost-interaction-free ensemble energies in a systematic and general way. Mapping the true interacting ensemble density onto such an approximate Hartree-only state-averaged ensemble leads to an alternative (in principle, exact) formulation of ensemble DFT. An exact ensemble exchange scheme is obtained along the same lines from the following approximate ensemble energy expression (note that, in practice, complementary fractions of exact and approximate density-functional expressions for the ensemble exchange energy are usually combined ):