Relativistic configuration-interaction calculations for the n=2 states of lithiumlike ions

Term energies are determined for the n=2 states of lithiumlike ions with nuclear charges in the range 10≤Z≤92. These calculations are based on the relativistic no-pair Hamiltonian, which includes both the Coulomb and the retarded Breit interactions. Single-particle wave functions are expanded in a B-spline basis constructed from Dirac-Slater orbitals restricted to a finite cavity. The Hamiltonian matrix is evaluated and Davidson’s method is used to determine the lowest few eigenenergies and eigenfunctions for each angular symmetry. Quantum electrodynamic and mass polarization corrections are also calculated. Precise agreement between theory and experiment for the 2s-2p transition energies is found throughout the Periodic Table.