Ionization potential of the lithium-like ground states from scandium to zinc

The ground state energies of the lithium-like systems from ScXIX to ZnXXVIII are calculated by using the full-core plus correlation method with multiconfiguration interaction wavefunctions. Relativistic and mass-polarization effects on the energy are evaluated perturbatively as the first-order corrections. The QED correction is also included. The predicted ionization potentials in this work are compared with the existing experimental data in the literature. The variation of the relativistic effect with the effective nuclear charge along this isoelectronic sequence is quantitatively discussed.