The article says "realistic (singular) potentials" but T. Kato did not have the opinion that the singular Coulomb potential is "real", rather he thought exactly the otherway round: The singular potential is an approximation to something "real" that can reflect additional structure. My claim comes from the following passage:
"In this sense the Coulomb potential can be regarded as a faithful and convenient approximation to the real potential in atomic systems." --(T. Kato, Fundamental properties of Hamiltonian operators of Schrödinger type, Trans. Amer. Math. Soc. 70 (1951) 195-211, last page)
If agreement on this can be met this should maybe changed (also in the german version) because there is sometimes a strange and harmful attitude in the physics community of Coulomb potentials being "real". Mpenz (talk) 11:02, 21 May 2015 (UTC)Reply