Comment on "Relativistic correction of the generalized oscillator strengthsum rules"

Romero and Aucar [Phys. Rev. A 57, 2212 (1998)] have found a vanishing resu lt for the relativistic correction to the dipole sum rule Delta S-1 for a o ne-electron system. They have given a result for the dipole sum rule Delta S-2 as well. We argue that these results are both incorrect and show explic itly that their approach yields a nonvanishing result for Delta S-1. The co rrected result is in agreement with that which we have obtained in a recent paper, in which we present explicit expressions for Delta S-1, Delta S-2, and several other more general sum rules.