Theoretical energies for the <i>n</i> = 1 and 2 states of the helium isoelectronic sequence up to <i>Z</i> = 100

The unified method described previously for combining high-precision nonrelativistic variational calculations with relativistic and quantum electrodynamic corrections is applied to the 1s 2 1 S 0 , 1s2s 1 S 0 , 1s2s 3 S 1 , 1s2p 1 P 1 , and 1s2p 3 P 0,1,2 staters of helium-like ions. Detailed tabulations are presented for all ions in the range 2 ≤ Z ≤ 100 and are compared with a wide range of experimental data up to 34 Kr + . The results for 90 U + significantly alter the recent Lamb shift measurement of Munger and Gould from 70.4 ± 8.3 to 71.0 ± 8.3 eV, in comparison with a revised theoretical value of 74.3 ± 0.4 eV. The improved agreement is due to the inclusion of higher order two-electron corrections in the present work.