2-ELECTRON SELF-ENERGY CONTRIBUTION TO THE GROUND-STATE ENERGY OF HELIUM-LIKE IONS

The two-electron self-energy contribution to the ground-state energy o f helium-like ions is calculated both for a point nucleus and an exten ded nucleus in a wide interval of Z. All the two-electron contribution s are compiled to obtain mast accurate Values for the two-electron par t of the ground-state energy of helium-like ions in the range Z = 20-1 00. The theoretical value of the ground-state energy of U-238(90+), ba sed on currently available theory, is evaluated to be -261382.9(8) eV, without higher-order one-electron QED corrections. (C) 1997 Published by Elsevier Science B.V.