On an approximation to the Schr\"odinger equation with the Hellmann   potential
  We tried to determine the range of validity of a recently proposed modification of the Hellmann potential that leads to analytical eigenvalues and eigenfunctions. We discuss the difficulties that we found in the analysis of the main equations and results. We conclude that the eigenvalues reported by the authors do not exhibit the same order as those of the Hellmann potential thus leading to a different underlying physics. What is more: the spectrum of the modified model is qualitatively different from the one supported by the Hellmann potential. 
Paolo Amore, Francisco M. Fern\'andez
quant-ph