Dramatic relativistic effects in atomization energy and volatility of the superheavy Hassium tetroxide and OsO4

Relativistic electronic structure studies on the heaviest elements

Spectacular developments in relativistic quantum theory and computational algorithms in the last two decades allowed for accurate predictions of properties of the heaviest elements and their experimental behaviour. The most recent works in this area of investigations are overviewed. Preference is given to those related to experimental research. The role of relativistic effects is elucidated.

Dissociation energy of ekaplutonium fluoride E126F: The first diatomic with molecular spinors consisting of g atomic spinors

Our ab initio all-electron fully relativistic Dirac-Fock (DF) and nonrelativistic (NR) Hartree-Fock (HF) self-consistent field (SCF) calculations predict the superheavy diatomic ekaplutonium fluoride E126F to be bound with the calculated dissociation energy of 7.44 and 10.46 eV at the predicted E126-F bond lengths of 2.03 and 2.18 Angstroms, respectively. The antibinding effects of relativity to the dissociation energy of E126F are approximately 3 eV. The predicted dissociation energy with both our NR HF and relativistic DF SCF wave functions is fairly large and is comparable to that for very stable diatomics. This is the first case, where in a diatomic, an atom has g orbital (l = 4) occupied in its ground state electronic configuration and such superheavy diatomics would have occupied molecular spinors (orbitals) consisting of g atomic spinors (orbitals). This opens up a whole new field of chemistry where g atomic spinors (orbitals) may be involved in electronic structure and chemical bonding of systems of superheavy elements with Z> or =122.

Relativistic effects on the electronic structure and volatility of group-8 tetroxides MO4, where M=Ru, Os, and element 108, Hs

The influence of relativistic effects on properties and volatility of the group-8 tetroxides MO4, where M=Ru, Os, and element 108, Hs, was studied on the basis of results of the fully relativistic (four component) and nonrelativistic density functional theory calculations. Relativistic effects were shown to increase bond strengths and decrease bond lengths in these molecules. They are responsible for a decrease in molecular polarizabilities and an increase in ionization potentials. The effects are much stronger in HsO4 than in the lighter congeners. Relativistic effects were also shown to slightly decrease dispersion interaction energies of RuO4, OsO4, and HsO4 with an inert (quartz or silicon nitride) surface, i.e., they increase volatility of these compounds as studied in the "one-atom-at-a-time" gas-phase chromatography experiments. They do, however, not influence the trend in group 8: both relativistically and nonrelativistically, volatility should change as RuO4<OsO4<HsO4. The reason for that is identical trends in the relativistic and nonrelativistic space distributions of the valence d electrons.

Calculated optical and magnetic properties of hexafluorouranate (V) anion: UF[sub 6][sup −]

Our ab initio all-electron Dirac-Fock and the corresponding nonrelativistic limit calculations performed at four U-F bond distances yield for octahedral UF(6) (-) the optimized U-F bond distance of 2.091 and 2.088 A, respectively. We have also performed Dirac scattered wave calculations at the optimized U-F bond distances using the first-order pertubational procedure to obtain the Zeeman and hyperfine magnetic tensors for the octahedral anion UF(6) (-). The calculated isotropic Zeeman tensor of Deltag=-2.87 is in fairly good agreement with the value of Deltag=-2.78+/-0.10 obtained in electron spin resonance experiments on the H(3)O(+)UF(6) (-) adduct and the unpaired electron-spin spends approximately 2.5% of its time on the fluorine 2p(3/2) spinors. The calculated relativistic transition energies of the near-IR and visible absorption bands are also in good agreement with the experimental results. The octahedral uranium hexafluoride anion has a simple crystal field f(1) configuration; however, relativistic four-component wave functions are necessary to interpret correctly the available magnetic data, while a relativistic treatment taking into account double group symmetrized basis functions should suffice for the interpretation of the optical data.