2. The second direction of development is towards the functional form. Currently, functionals are borrowed from the Kohn-Sham world, but specific functionals for this theory should eventually be developed. One possibility is to develop multiconfigurational density-driven functional methods that correct the classical or total energy of a multiconfigurational wave-function method through the use of a machine-learned functional. 492 A promising alternative to variants of single-determinantal Kohn-Sham DFT, including hybrid and longrange corrected DFT, is to use range separation not only for the exchange energy but also for the correlation energy, as originally suggested by Savin 158 and mentioned by him in contribution (2.2.24); see also contributions (2.5.6) and (2.5.7) from Pernal.