A simple interpolation formula for the spectra of power-law and log   potentials
  Non-relativistic potential models are considered of the pure power V(r)=sgn(q) r^q and logarithmic V(r)=ln(r) types. It is shown that, from the spectral viewpoint, these potentials are actually in a single family. The log spectra can be obtained from the power spectra by the limit q --> 0 taken in a smooth representation P(n,l,q) for the eigenvalues E(n,l,q). A simple approximation formula is developed which yields the first thirty eigenvalues with error < 0.04%. 
Richard L. Hall