Effective Mass Dirac--Morse Problem with any κ-value

The Dirac-Morse problem is investigated within the framework of an approximation to the term proportional to 1/r² in the view of the position-dependent mass formalism. The energy eigenvalues and corresponding wave functions are obtained by using the parametric generalization of the Nikiforov-Uvarov method for any κ-value. We also study the approximate energy eigenvalues, and the corresponding wave functions in the case of the constant-mass for pseudospin, and spin cases, respectively.