High-precision ab initio calculations of the spectrum of Lr+

The planned measurement of optical resonances in singly ionized lawrencium (Z=103) requires accurate theoretical predictions to narrow the search window. We present high-precision, ab initio calculations of the electronic spectra of Lr+ and its lighter homologue lutetium (Z=71). We have employed the state-of-the-art relativistic Fock space coupled cluster approach as well as the configuration interaction with many-body perturbation theory (CI+MBPT) method to calculate atomic energy levels, g factors, and transition amplitudes and branching ratios. Our calculations are in close agreement with experimentally measured energy levels and transition strengths for the homologue Lu+, and are well converged for Lr+, where we expect a similar level of accuracy. These results present large-scale, systematic calculations of Lr+ and will serve to guide future experimental studies of this ion.