(2.1.7) Yang : I agree with Savin on the difficulty of semilocal functionals. The example of the interaction energy of a oneelectron system is a clear case: the exact exchange-correlation energy has to cancel the classical Coulomb energy. Otherwise, the functional has a self-interaction error (SIE). For many years, the SIE had been assumed to be the main systematic error in DFAs, related to the incorrect dissociation of molecular ions, the underestimation of chemical reaction barriers and band gaps of molecules and bulk materials, the overestimation of polymer polarizability, and many other failure of commonly used DFAs. However, the development of two SIE-free functionals, the Becke05 and the MCY2 14 functionals, changed the understanding. While these two exchange-correlation func-tionals, nonlocal and also nonsemilocal, are SIE-free by construction for any one-electron system and perform as well on thermodynamics benchmarks as hybrid functionals, they still retain significant errors in the dissociation of molecular ions, band gaps of molecules, and polymer polarizability problems, much like the hybrid functional of B3LYP. The only significant improvement observed is in the prediction of reaction barriers. Thus the systematic error is clearly not the SIE.