Relativistic configuration-interaction calculations of the energy levels of the 1s22l and 1s2l2l′ states in lithiumlike ions: Carbon through chlorine

We present systematic calculations of energy levels of the 1s22l and 1s2l2l' states of ions along the lithium isoelectronic sequence from carbon to chlorine. The calculations are performed by using the relativistic configuration-interaction method adapted to the treatment of autoionizing core-excited states. The relativistic energies are supplemented with the QED energy shifts calculated within the model QED operator approach. A systematic estimation of the theoretical uncertainties is performed for every electronic state and every nuclear charge. The results are in agreement with existing high-precision theoretical and experimental data for the ground and first excited states. For the core-excited states, our theory is much more accurate than the presently available measurements.