Consider the long-range Coulomb potential in the hydrogen atom shielded for small distances. The shielding should be modeled by a quadratic potential, as you know it from the harmonic oscillator
(a) Determine the parameters ? and V_0 in such a way that the two potentials at the point r_0 merge into one another in a continuously differentiable manner and plot the potential together with the unshielded Coulomb potential for r_0 = a_0, r_0 = a_0/5 and r_0 = 5a_0, where a_0 is the Bohr radius is.
(b) Qualitatively describe your expectation of how the shielding will affect the bound-state energies as a function of n, ? and m for the different values ??of r_0. In particular, discuss the question of degeneracy and the number of bound states.