  Virial relations for the Dirac equation in a central field and their
applications to calculations of H-like atoms are considered. It is demonstrated
that using these relations allows one to evaluate various average values for a
hydrogenlike atom. The corresponding relations for non-diagonal matrix elements
provide an effective method for analytical evaluations of infinite sums that
occur in calculations based on using the reduced Coulomb-Green function. In
particular, this method can be used for calculations of higher-order
corrections to the hyperfine splitting and to the g factor in hydrogenlike
atoms.
