Molecular dynamics of liquids in relation to the solid and gas phases as seen by neutron scattering

Abstract

A short review is given on the results of neutron inelastic scattering studies of some simple liquids. The nature of the diffusion process is discussed from the standpoint of these experiments. A model is described for the centre-of-mass motion of a molecule, using which an attempt is made to incorporate both vibratory many-body behaviour at lower temperatures and binary collision behaviour at higher temperatures. An explicit expression is obtained for the diffusion constant. The rotational motion of the molecule is also incorporated in the model. Comparison with some experimental results on solids and on liquid propane is reported.