Physical Review A
The aim of this paper is to test a simple method for converting accurate nonrelativistic predictions of atomic properties into accurate relativistic predictions with a minimum of additional computational effort. The method connects smoothly the exact nonrelativistic LS-coupling results appropriate at small Z with the relativistic jj-coupling results appropriate at large Z. For the processes stated in the title, the method appears to offer a significant improvement in accuracy over relativistic Hartree-Fock or random-phase- approximation calculations, particularly in the low and intermediate range of nuclear charge. For large Z, the present results agree well with the relativistic random-phase approximation. © 1979 The American Physical Society.
Drake, Gordon W. F.. (1979). Unified relativistic theory for 1s2p P13-1s2 S01 and 1s2p P11-1s2 S01 frequencies and transition rates in heliumlike ions. Physical Review A, 19 (4), 1387-1397.