Algebraic approach to pseudospin symmetry for the Dirac equation with scalar and vector modified Pöschl-Teller potentials

By the algebraic method we study the approximate solution to the Dirac equation with scalar and vector modified Pöschl-Teller (MPT) potentials carrying pseudospin symmetry. The transcendental energy equation and spinor wave functions with arbitrary spin-orbit coupling quantum number k are presented. It is found that there exist only negative-energy states for bound states under pseudospin symmetry, and the energy levels will approach a constant when the potential parameter α goes to zero. There also exist the corresponding degenerate states between $(n+1, k- 2)$ and $(n, k)$ in the case of pseudospin symmetry