Relativistic effects on atomic electronic shells

The second (indirect) relativistic effect is responsible for the expansion of outer d and f orbitals Here the relativistic contraction of the s and pi/2 shells results in a more efficient screening of the nuclear charge, and the outer high angular momentum orbitals expand and become energetically destabilized. In turn, the relativistically expanded d and f orbitals cause a small additional 

The third relativistic effect is the well-known spin-orbit (SO) coupling important for 1 0 levels (p, d, f,. .. electrons) which split into j = 1 Vi. It also originates from the inner shell region in the vicinity of the nucleus. 

In transactinide compounds the SO coupling becomes similar, or even larger, in size compared to typical bond energies. The splitting of the 6d levels is, for example, 3.27 eV in element 112 (Fig. 6). 

The SO splitting of the valence 7p electrons in elements 113 through 117 is several eVs (Fig. 7), and it is 11.8 eV in element 118 (Fig. 8). Comparison of the relativistic with nonrelativistic AO energies for group-18 elements is also shown in Fig. 8. All three relativistic effects are of the same order of magnitude and they grow roughly as 7.  

Breit effects (accounting for magnetostatic interaction) on valence orbital energies and on ionization potentials (IP) of the heaviest elements are small, for example, only 0.02 eV for element 121 [60]. They can, however, reach few % for the fine structure level splitting in tiie 7p elements and are of the order of correlation effects there. In element 121, they can be as large as 0.1 eV for transition energies between states including f orbitals [60]. 

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