RISM calculation of the structure of liquid acetonitrile

Abstract

The RISM equation is used to study the local structure of acetonitrile. The theoretical calculations predict neutron and X-ray scattering structure factors that are in good agreement with experiment. The following conclusions are drawn from this study. (1) Dipole-dipole interactions play, at most, a minor role in forming the structure of liquid acetonitrile. (2) Even though dipole-dipole interactions are not very significant, there are strong orientational correlations between neighbouring molecules. (3) These pair correlations are similar to those found in liquid carbon disulphide (a non-polar fluid), and are determined primarily by the molecular shape. (4) The accuracy attainable in present neutron diffraction determinations of liquid structure must be improved by an order of magnitude for the effects of dipole-dipole interactions to be discernible in such experiments.