Potential energy curves mixed valence complexes

Expressions (1) and (2) are the basis for the Hush-Marcus model. They allow the construction of potential energy curves of parabolic shapes, when the energy is plotted as a function of a composite reaction coordinate. These curves in turn are the basis for an elementary description of the thermal and optical processes in mixed valences complexes. In principle, it is possible to compute a rate constant from this model, using the total reorganization energy as an activation energy and introducing an electronic transmission factor calculated by the Landau-Zener formula. However this procedure is now supplanted by the quantum models. 

Figure 2 Potential curves for a mixed-valence dinuclear complex (A+---A) as functions of the energy gap reaction coordinate X. Broken lines (a), no electronic interaction (b,b), (c,c), (d,d), successively stronger interactions, the last corresponding to Hab > A/2 (see text) so that the symmetrical structure is the most stable. The vertical arrow indicates an intervalence charge-transfer transition...

---