Ionisation potentials and energy levels of ions of heavy and superheavy elements Te, I, Po, At, Lv and Ts

We calculate the energy levels and successive ionisation potentials (IPs) of ions of the three heaviest known Group 16 and 17 elements using a theoretical approach that combines the linearised coupled-cluster method, configuration interaction, and perturbation theory. Our calculations address critical gaps in the available data on the electronic structure of the superheavy elements livermorium (Lv) and tennessine (Ts), as well as their lighter homologues polonium (Po) and astatine (At). To assess the accuracy of our methods, we perform analogous calculations for the lighter homologues tellurium (Te) and iodine (I), for which both experimental and reliable theoretical data are available for comparison.