The program calculates the energy levels of a valance electron for
the following electrostatic potential: Z protons in the nucleus
plus n "screening" electrons uniformly distributed in a solid sphere of
radius c. That is the electric potential is a Coulomb potential for a point
source with charge +Ze surrounded by a uniformly charged sphere
of radius c that has a total charge of -ne.
The results listed are energies for bound states between zero and
-estart for the different values of orbital
angular momentum l. Good choices are estart around 10 eV
and 0.3 < c < 0.6. Setting
c=0.01 lets one check the case for the point Coulomb potential.
As c is increased, the levels decrease in energy.