Finally, the parameter C GDD = 0.885 in eq. 5 was determined for use with LRC-ωPBE, in order to reproduce IE-tuning results. That value is used throughout this work. Smaller values of C GDD have been optimized for LRC functionals with c hfx > 0. Since both w(r) and d 2 x (r) are functionals of ρ(r), GDD tuning must be seeded with a self-consistent DFT calculation. As in previous work, LRC-ωPBE with ω = 0.3 bohr -1 is used for that purpose. The density thus obtained is used to evaluate d 2