Correlation, Relativistic and Quantum Electrodynamics Effects on the Atomic Structure of eka-Thorium

Large-scale multiconfiguration Dirac-Fock calculations have been performed for the superheavy element eka-thorium, $Z=122$. The resulting atomic structure is compared with that obtained by various computational approaches involving different degrees of approximation in order to elucidate the role that correlation, relativistic, Breit, and quantum electrodynamics corrections play in determining the low-energy atomic spectrum. The accuracy of the calculations is assessed by comparing theoretical results obtained for thorium with available experimental data.