10 0 10 20 30 40 50 60 70 80 90 100 -0.60 -0.55 -0.50 -0.45 -0.40 2$^{3}$S 0 10 20 30 40 50 60 70 80 90 100 -4.4 -4.2 -4.0 -3.8 -3.6 -3.4 -3.2 -3.0 G(Z) Z Z Z Z 1$^{1}$S G(Z) Z 0 10 20 30 40 50 60 70 80 90 100 -1.06 -1.04 -1.02 -1.00 -0.98 -0.96 -0.94 2$^{1}$S 0 10 20 30 40 50 60 70 80 90 100 -1.0 -0.9 -0.8 -0.7 -0.6 2$^{3}$P$_{0}$ 0 10 20 30 40 50 60 70 80 90 100 -0.16 -0.15 -0.14 -0.13 2$^{3}$P$_{2}$ FIG. 1: The higher-order remainder function G ( Z ) from Eq. (35) inferred from the all-order numerical results of Ref. [8] for the two-electron QED correction, in comparison with the Z = 0 limit obtained by fitting the 1 /Z expansion of the mα 6 correction calculated in this work (denoted by the cross on the y axis). The all-order results for Z smaller than 30 (in some cases, 20) were left out since their numerical accuracy turns out to be not high enough. 1999), p. 101. Phys. 80 , 633 (2008). [20] V. A. Yerokhin, Phys. Rev. A 80 , 040501(R) (2009). [21] V. I. Korobov, Phys. Rev. A 61 , 064503 (2000). [22] V. I. Korobov, Phys. Rev. A 66 , 024501 (2002). [23] C. Schwartz, Int. J. Mod. Phys. E 15 , 877 (2006). [24] G. W. F. Drake and S. P. Goldman, Can. J. Phys. 77 , 835 (1999). [34] C. Schwartz, Phys. Rev. 123 , 1700 (1961). [35] V. I. Korobov and S. V. Korobov, Phys. Rev. A 59 , 3394 (1999). [36] V. M. Shabaev and A. N. Artemyev, J. Phys. B 27 , 1307 (1994). [37] E. Riis, A. G. Sinclair, O. Poulsen, G. W. F. Drake, W. R. C. Rowley, and A. P. Levick, Phys. Rev. A 49 , 207 (1994). [38] T. J. Scholl, R. Cameron, S. D. Rosner, L. Zhang, R. A. Holt, C. J. Sansonetti, and J. D. Gillaspy, Phys. Rev. Lett. 71 , 2188 (1993). [39] T. P. Dinneen, N. Berrah-Mansour, H. G. Berry, L. Young, and R. C. Pardo, Phys. Rev. Lett. 66 , 2859 (1991). [25] V. I. Korobov, Phys. Rev. A 69 , 054501 (2004). [26] G. W. F. Drake and R. A. Swainson, Phys. Rev. A 41 , 1243 (1990). [27] V. I. Korobov, private communication. [28] I. Angeli, At. Data Nucl. Data Tables 87 , 185 (2004). [29] P. J. Mohr, Phys. Rev. A 32 , 1949 (1985). [30] G. Audi, A. H. Wapstra, and C. Thibault, Nucl. Phys. A729 , 337 (2003). [31] G. W. F. Drake, in Handbook of Atomic, Molecular, and Optical Physics , ed. by G. W. F. Drake (Springer, NY, 2006). [40] N. J. Peacock, M. F. Stamp, and J. D. Silver, Phys. Scr. T8 , 10 (1984). [41] W. A. Hallett, D. D. Dietrich, and J. D. Silver, Phys. Rev. A 47 , 1130 (1993). [42] T. J. Scholl, R. A. Holt, and S. D. Rosner, Phys. Rev. A 39 , 1163 (1989). [43] J. K. Thompson, D. J. H. Howie, and E. G. Myers, Phys. Rev. A 57 , 180 (1998). [32] P. J. Mohr and B. N. Taylor, Rev. Mod. Phys. 77 , 1 (2005). [33] R. S. Jr. Van Dyck, D. L. Farnham, S. L. Zafonte, and P. B. Schwinberg, in Trapped Charged Particles and Fun- damental Physics , ed. by D. H. E. Dubin and D. Schnei- der, AIP Conf. Proc. No. 457 (AIP, Woodbury, NY,