Atomic Eigenvalues and Electronic Configurations of the Atom

This competition, manifested in the structure of the actinide atomic spectra, also appears as a competition between configurations there is an accumulation of many configurations, both even and odd, at about the same height, leading to a high density of energy levels (in fact, we had arrived at the same conclusion by inspecting Fig. 1 in Sect. A.I.2). 

The energy level values of the lowest spectroscopic term of the electronic configuration of lanthanide as well as actinide atoms, were tabulated by Brewer. Such tables are very useful for phenomenological correlations concerning actinide metals (see Chap. C). From these tables one can obtain Table 1 giving the ground state and the first excited level of the actinide atoms as well as of the lanthanide atoms for comparison  

When the f sub-shell is less than half-filled the stabilization of the divalent state (f ) relative to the trivalent state is more rapid for the lanthanides than for the actinides. But the behaviour is reversed in the second half of the series. In part, this must be due to the low binding energy of the 6 d electrons compared to the 5 d. 

General Concepts in Actinide Solid State Physics 

Since band theory has proved an invaluable tool for the description of the light actinide solids. Sects. 1 and 2 will be devoted to the band description and to its limits. Sect. 3 analysing in more details the band one-electron Hamiltonian, and the ways it can be written in order to take into account electron-electron interaction. 

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