Methyl-like quantum rotor dynamics

The Dynamics of Methyl-like Quantum Rotors in NMR Spectra... 

THE DYNAMICS OF METHYL-LIKE QUANTUM ROTORS IN NMR SPECTRA... 

A consistently quantum mechanical theory describing the coherent and stochastic dynamics of tetrahedral rotors has not been reported yet. Nevertheless, in the extreme situations where the facile re-orientations involve only one axis, the DQR theory will be rigorously valid also for such rotors. Specifically, if the unique axis is a three-fold axis, the stochastic term will have the same form as in Eq. (8) [or the equivalent form in Eq. (10)]. In the case of a two-fold axis, the AB term such as that in Eq. (5) will be obtained, but with the pair-permutation operator P replaced by the operator R defined above. One can thus reasonably expect that even in the cases where there are more than one facile re-orientation axes, applicability of the phenomenological AB approach will suffer similar restrictions as those specified in Subsection 4.4 for methyl-like rotors. 

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