Molecular dynamics study of local structure and reorientational dynamics in liquid acetonitrile

Abstract

Local structure and reorientational dynamics in liquid acetonitrile, which are related to intensities and band shapes of the far-infrared spectra, were studied by molecular dynamics calculations. The calculations were performed at 233, 291 and 350 K with two types of potential, with and without Coulomb terms involving fractional charges on each atom in addition to the atom-atom Lennard-Jones terms. Comparison of results of the two types of calculations, MD(LJ + FC) and MD(LJ), shows that the dipole-dipole interaction plays an important role in determining the average local structure and the intermolecular cross-correlation of the reorientational motion. The result of MD(LJ + FC) reproduces well both a relative enlargement of the molecular dipole moment in the liquid phase and a characteristic feature of the rotational velocity correlation function.