  The spatial distribution of electric charges forming a square well potential
has been analyzed. It is shown that this potential is created by two concentric
spheres with a double layer of charges. A C60 shell potential has been
calculated under the assumption that it is formed by the averaged charge
density of a neutral atom. It is further demonstrated that the phenomenological
potentials simulating the C60 shell potential belong to a family of potentials
with a non-flat bottom. Two possible types of C60 model potentials are proposed
and their parameters have been calculated. AMS (MOS) Subject Classification.
62P35, 81V55
