Taming the Electronic Structure of Lead and Eka-lead (Flerovium) by the Relativistic Coupled Cluster Method

Abstract

Theoretical investigations of the super-heavy elements (SHEs) are extremely challenging and are often the sole source of useful chemical information. Relativistic Fock-space multireference coupled cluster (RFS-MRCC) computations have been carried out for evaluating the ionization potential (IP), excitation energies (EE), nuclear magnetic hyperfine constant ($A$), lifetime ($\tau$) and Land{\'e} $g$ factor of eka-lead (Fl). To judge the accuracy of Fl results, similar calculations are performed for Pb, which shows a nice and consistent agreement with known experimental values. Thus, we believe that our predictions for Fl are reliable and useful for the simulation of experimental behavior. To the best of our knowledge, no prior theoretical and/or experimental information is available for $A$, $\tau$ and g-factor of this SHE. The higher IPs and EEs of Fl with respect to Pb, indicate the former to be more inert and less metallic than Pb. This is contingent on the effects of the relativistic stabilization of the $7s$ and $7p_{1/2}$ orbitals. The present analysis demonstrates the influence of higher-body cluster operators on atomic properties. The close agreement with experiment (having an estimated error within 1-2\%) indicates that the FS-MRCC method is a reliable predictive tool in cases where the experimental results are not readily available, such as the SHEs. The remaining source of error possibly stems out from the omission of the full-blown triple virtual excitations and the absence of Breit interaction.