The bound eigenfunctions and spectrum of a Dirac hydrogen atom are found takmg advantage of the SU(1, 1) Lie algebra in which the radial part of the problem can be expressed. For defining the algebra we need to add to the description an additional angular variable playing essentially the role of a phase. The operators spanning the algebra are used for defining ladder operators for the radial eigenfunctions of the relativistic hydrogen atom and for evaluating its energy spectrum. The status of the Johnson-Lippman operator in this algebra is also investigated. ©
2005 Elsevier B.V. All rights reserved.