Tests of QED in two-electron ions. IV. A status report

For pt.III see ibid., vol.16, p.L433-6 (1983). The variety of approximations used in estimation of the wavelengths of 1s2s 3S-1s2p 3P lines studied in this series reveals the need for a status report. Two new features are discussed: the need for basis set extrapolation at the low-Z end of the isoelectronic sequence, and an estimate of two-body corrections to the electron self-energy. The recommended theoretical values lie mostly within experimental error estimates for Z<10. For higher values of Z the authors propose to change to the values given in the second paper (1983) of this series.