The effects of NH3 free rotation on the inelastic neutron scattering spectrum of Ni(NH3)2Ni(CN)4·2C6D6 at 20 K

Quantitative atom-atom potentials from rotational tunneling: their extraction and their use

Rotational tunneling of small molecular groups has been the subject of considerable theoretical and experimental activity for several decades. Much of this activity has been driven by the promise of exploiting the extreme sensitivity of quantum tunneling to interatomic potentials, but until recently, there was no straightforward means by which quantitative information about these potentials could be extracted. This review explains how a quantitative method, suitable for general application, was developed. It then goes on to show how this has been used to understand tunneling systems for which no previous satisfactory explanation had been found. The application of the methodology, and its results, to other disciplines is discussed.