The "repulsion" or "screening" density ρ rep (r) effectively mimics the repulsion felt by each electron. For a system of N electrons in a self-interaction-free theory, the integrated charge Q rep of ρ rep (r) should be Q rep = N -1, because each electron is repelled by the other N -1 electrons but not by itself. However, in local and semilocal DFAs, Q rep = N, which we interpret to imply that each Kohn-Sham electron is effectively repelled by all electrons of the system, including itself, and so self-interaction is present.