Free binding energy first

We can understand the behaviour of the binding energy curves of monovalent sodium and other polyvalent metals by considering the metallic bond as arising from the immersion of an ionic lattice of empty core pseudopotentials into a free-electron gas as illustrated schematically in Fig. 5.15. We have seen that the pseudopotentials will only perturb the free-electron gas weakly so that, as a first approximation, we may assume that the free-electron gas remains uniformly distributed throughout the metal. Thus, the total binding energy per atom may be written as... 

In other words, the intrinsic binding energies of the two steps are additive but not the entropy losses [130], which means that the intrinsic binding free energy of the first step AG1 (carb) contributes to NCA stabilization. On the other hand, free energies corresponding to the overall entropy losses as-... 

The IS — 2S transition obeys the selection rule AF = 0, Am = 0 and is almost field-independent However, the g-factor for the bound electron is slightly less than for free space due to relativistic effects, and this gives the transition a small first-order field dependence. In the IS state the g-factor is g(lS) = g0 (1 - a2/3) [10]. The relativistic term is proportional to the binding energy so that g(2S) = ge (1 - a2/12). Thus, the field-dependence of the transition IS- 2S, (F=l,m=l AF=0,Am=0) leads to a frequency shift... 

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