Nuclear-size correction to the one-loop self-energy in hydrogenlike ions

The nuclear-size effect on both diagonal and off-diagonal one-loop self-energy matrix elements is considered for hydrogenlike ions with Z=60, 82, 90, and 92. Specifically, the 1s, 2s, 3s, 2p_1/2, and 2p_3/2 states, as well as the off-diagonal 1s-2s, 1s-3s, and 2s-3s matrix elements, are considered. The calculations are performed within the rigorous quantum-electrodynamics framework, nonperturbatively in the nuclear-strength parameter \alpha Z. Excellent agreement is found with results reported in the literature. Simple and useful approximate formulas to treat the nuclear-size correction are obtained, which, in particular, can be used to study the self-energy contributions to the field-shift factors.