High-Z Benchmarking: Probing the Sub-eV Frontier and an Extensive Li-like Uranium Atomic Dataset

Recent theoretical investigations into the excitation energies of the high-Z lithium isoelectronic sequence (Li-like ions) have revealed significant discrepancies of up to about 40 eV. In this work, we address this issue through a comprehensive study of Li-like uranium (U89+), calculating the lowest 35 levels of the 1s2nl (n<=6) configurations.We employ two independent relativistic methods: the multiconfiguration Dirac--Hartree--Fock (MCDHF) method implemented in the GRASP2K code, and the relativistic configuration interaction (RCI) method within the Flexible Atomic Code (FAC). Our results resolve the discrepancies, achieving excellent mutual agreement and reducing deviations from experiment to within about 2 eV. Furthermore, we identify the bottlenecks to achieving sub-electronvolt (sub-eV) accuracy for each method in the strong-field, high-Z regime.To the best of our knowledge, this is the most extensive dataset for this ion to date, including excitation energies, lifetimes, and radiative properties for allowed (E1) and forbidden (M1, E2, M2) transitions.Estimated uncertainties for most strong allowed and forbidden transitions remain below 1% and 2%, respectively, rendering this dataset valuable for applications in plasma spectroscopy.The Table A and Table 3 (complete table) are presented here (only on this website). Table A：MCDHF transition parameters for E1 and E2 transitions in U89+. The table presents the transition wavelength $\lambda$ (in \AA), the radiative rates in both length ($A_{\rm L}$) and velocity ($A_{\rm V}$) gauges (in s-1), and their relative deviation dT. Table 3 (complete table) Length--gauge transition properties for U89+ obtained from the present MCDHF and RCI calculations, the table lists data for both allowed (E1) and forbidden (M1, E2, and M2) transitions.