Radical pair energy, variation

The principal concern in radical pair theory is not which state is of lower energy but rather the energy difference and its variation as the length of the box or the inter-radical distance in the radical pair changes. Further, AEsi is time-dependent because the inter-radical distance fluctuates with time. As the separation gets larger, decreases... 

Fig. 7. Variation of the electron exchange energy for radical pairs during a random walk .

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