RELATIVISTIC Z-DEPENDENT CORRECTIONS FOR LI-LIKE AND BE-LIKE IONS

Energies of the ten (2l2l') states of ions of the beryllium isoelectro nic sequence are determined to second order in relativistic many-body perturbation theory starting from hydrogenic basis functions. Both the second-order Coulomb interaction and the second-order Breit-Coulomb i nteraction are included Each diagram contribution is represented as a power series in Z. The leading term of each diagram gives the nonrelat ivistic limit which coincides with the contribution obtained starting with nonrelativistic basis functions. We obtain numerical data for the relativistic corrections for 2l states of Li-like ions and for (2l2l' ) states of Be-like ions.