Uranium, electronic structure

Ground-state configuration and electronic structure of the monomeric uranium(III) alkyl [t 5-(CH3)5C5]2UCF[[Si(CF[3)3]2 were investigated and reported... 

The electronic structures of the two forms continue to claim attention. An XPS examination of macrocrystalline /3 UD3, which incidentally is not spontaneously flammable in air, showed a large density of states near the Fermi level. The f electrons appear in both localized and delocalized orbitals. There are two uranium sites in the cell One kind appears responsible for the metallic conduction and the other, with localized f orbitals, for the paramagnetism (315, 321). 

The bonding and electronic structure of these adducts have been explored using X a SW molecular orbital calculations. These indicate that back-bonding, perhaps from the 5f orbitals on the uranium, may be of some importance, at least in the case of the carbonyl (382). (For other reactions of UCp3, see Section V,A,3.)... 

Since the uranyl nitrate is the most stable and fundamental species of uranium in nitric acid solutions, information on the electronic structure of this complex provides a basis of understanding stability of uranium species in solution. Information on strength of bonding between uranium and the ligands such as water and organic species is the major concern for design of novel extractants for the selective separation of the actinides. 

The DV-DFS molecular orbital(MO) method is based on the Dirac-Fock-Slater approximation. This method provides a powerful tool for the study of the electronic structures of molecules containing heavy elements such as uranium[7,8,9,10]. The one-electron molecular Hamiltonian in the Dirac-Fock-Slater MO method is written as... 

The energy of the/-states moves up with increasing 5 / electron number and the sensitivity of the position of the 5/ states is greater in the a = 1 case. The 5/ bands are found to be hybridized with the very broad 7 sp band and the broad 6 d band, but for a = 1 they appear to be very flat. For a = 2/3, the / bands are wider and the ividth remains lower than 0.1 Ryd then the hybridization with the d band increases. According to A. J. Freeman, the uranium band structure could be understood as that of a transition metal with 5/bands superimposed on the d-s bands and hybridized with them. 

For an atom as heavy as uranium theoretical treatments of the molecular electronic structure are strongly dependent on simplifying assumptions so it is best to turn first to experiment for the basis of any analysis. This topic has been reviewed previously, but the interpretation of the experimental data has remained ambiguous and controversial [23], It is the purpose of this review to bring the experimental position up to date, and to show that most of the uncertainties have now been resolved. The review is not exhaustive I have selected only the most significant sources. 

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