Shielding surface rovibrational averaging

Shielding Surfaces and Rovibrational Averaging. - For shielding calculations to mimic exactly what is observed in experiment, not only does one require an accurate equilibrium geometry but also an incorporation of rovibrational averaging is necessary. As an example, Astrand and Ruud have demonstrated that the rovibrational corrections to shielding in the case of in 2-fluorobutane... 

Isotope Shifts. - Isotope shifts are intimately related to rovibrational corrections. Thus, with the same shielding surfaces used for rovibrational averaging, one can extract expected changes in chemical shift due to isotope substitution. This is once again illustrated in Dransfeld s work, which is cited near the beginning of the preceding section. Here too, some cautionary words are in... 

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