We apply a recently developed method [V. A. Dzuba, Phys. Rev. A 90, 012517 (2014); J. S. M. Ginges and V. A. Dzuba, Phys. Rev. A 91, 042505 (2015)] to calculate energy levels of superheavy elements Uut $\left(Z=113\right)$, Fl $\left(Z=114\right)$, and ${\mathrm{Fl}}^{+}$. The method combines the linearized single-double coupled-cluster technique, the all-order correlation potential method, and configuration-interaction method. Breit and quantum electrodynamic corrections are included. The role of relativistic and correlation effects is discussed. Similar calculations for Tl, Pb, and ${\mathrm{Pb}}^{+}$ are used to gauge the accuracy of the calculations.

• Received 29 August 2016

DOI:https://doi.org/10.1103/PhysRevA.94.052501