Vibronic interactions, definition

The following equations for the Eg (g> Sg and T2g Sg vibronic interaction of a d cation and some definitions supply the necessary background from theory ... 

It is worthy to give a direct definition of CITE. CITE is virtual phonon exchange at electron orbital degeneracy, leading to the correlation of local distortions and selfconsistent correlation of electrons. The virtual phonon exchange is the result of electron-phonon (vibronic) interaction and of phonon dispersion. 

The aim of this work is to elucidate these problems. To this end, we calculate the effective spin Hamiltonian of the 5f2—5f2 superexchange interaction between the neighboring U4+ ions in the cubic crystal lattice of UO2 and we calculate T5 <%> eg, rs f2g(l) ancl r5 f2g(2) linear vibronic coupling constants. These data are then used to draw a more definite conclusion about the driving force of the phase transition and especially about the actual mechanism of the spin and orbital ordering in U02. 

The situation might be different at very low temperatures, where more complicated molecules such as the components of biological systems could possess spectra with definite vibronic structure. In this case, a transfer rate proportional to the first power of the interaction energy, as has been suggested recently , would be possible. This, however, seems unimportant, as long as we are not concerned with biological conditions in outer space ... 

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