Jump /jumping angle, random above

SRPAC spectra of Fig. 9.33a with a model that allows random, single-activated jumps of the EFG on a cone (Fig. 9.33b) was possible over the entire temperature range. This random jump cone model follows an Arrhenius law with activation energy a = (20.1 0.8) kJ moP and frequency factor A = (5.5 1.6) 10 s and it yields a cone opening angle of about 47° above 380 K [81]. 

The Dejean-Laupretre-Monnerie (DLM) orientation autocorrelation function is based on the above description. It takes into account independent damped conformational jumps, described by the Hall-Helfand autocorrelation function, and librations of the internuclear vectors represented, as proposed by Howarth [17] (see chapter 4) by a random anisotropic fast reorientation of the CH vector inside a cone of half-angle and axis the rest position of the internuclear vector. The resulting orientation autocorrelation function can be written as... 

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