(2.1.16) Scheffler : I somehow disagree with the last sentence of contribution (2.1.13). Clearly, Kohn-Sham theory has provided us with significant understanding, for polyatomic systems, mostly for cases where the physics is largely governed by the independent-particle kinetic-energy operator (or its orbitals). However, in general, I would hesitate to call Kohn-Sham theory together with the known DFAs "(sufficiently) accurate". A key scientific problem is that the range of validity of the known DFAs is unknown, and a reliable estimate of the accuracy and a systematic convergence of the accuracy are not possible. Our own pragmatic approach is to perform calculations with different DFAs, and if the results are similar, we tend to accept them. Otherwise, we are worried. And, if possible, we check final results by a higher-level theory -by, for example, coupled-cluster theory.