Dirac eigenvalues for screened Coulomb potentials

A single fermion is considered, moving in a screened Coulomb potential having the form V(r) = g(-1/r), where g is monotone increasing and concave. The method of potential envelopes is applied to this problem and it is shown that close approximations for the relativistic eigenvalues are given by a simple Specific results for the first four eigenvalues of the atoms Z = 14(5)84 are compared to corresponding accurate values found numerically by the use of Dirac spinor orbits. (author)