Eka-lead element 114 - an island of stability

Two series of calculations were carried out [97]. The first started from the closed-shell ion, adding two electrons in the Fock-space scheme 

The closed-shell ns state is taken as reference in the second Fock-space sequence, 

Here 34 electrons are correlated in the reference state. Basis sets going to I = 8 were used, with 35s26p21dl6/llp9h9i7A 7/ Gaussian orbitals. The FSCC iterations converge only when the np orbitals serve as the sole valence particles, i.e., only ns np states could be obtained. The IHFSCC method allows many more valence orbitals and, consequently, many more states. The Pm for lead included all states constructed from the 7s, 8s, 6p, 7p, and %d orbitals P included, in addition, states with occupied 9s — 12s, 8p — lip, 7d — 9d, 5/ — 7/, and 5g orbitals. For E114 we were interested in fewer states, so that Pm was smaller, with 8s, 7p, and 8p orbitals 9s — 13s, 9p — I2p, 7d — lOd, 6/ — 8/, and bg orbitals complete the P space. 

The ionization potentials and low excitation energies of the lead and eka-lead cations are reported, together with Pb experimental values [59], in Table 19. For easy comparison, terms are listed in the LS coupling as 

The most prominent featme of the energies collected in Tables 19 and 20 is that ionization potentials and excitation energies of El 14 are much 

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