Tensor coupling and relativistic spin and pseudospin symmetries with the   Hellmann potential
  The Hellmann potential is a superposition potential that consists of an attractive Coulomb potential and a Yukawa potential. By using the generalized parametric Nikiforov-Uvarov (NU) method, we have studied the approximate analytical solutions of the Dirac equation with the Hellmann potential including a Coulomb-like tensor potential for arbitrary spin-orbit quantum number k under the presence of exact spin and pseudo-spin (p-spin) symmetries. We show that tensor interaction removes degeneracies between spin and pseudospin doublets. As particular cases, we found the energy levels of non-relativistic case and also the pure Coulomb potential energy levels. 
A. A. Rajabi, M. Hamzavi
quant-ph