Jump-motion in crystals

A jump-motion about an axis of symmetry is a common example of initial large-amplitude motion on the path from a rigid crystal to the melt. It could be identified 

For the heat capacity data see R. A. Ruehrwein and T M Powell, J. Am Chem. 

For the NMR data see M R. J. Hoch and F.A. Rushworth, in Nuclear Magnetic Resonance in Chemistry. B. Resce, ed.. Acad. Press, New York, p. 343 (1965). 

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