The far infrared absorption spectrum of liquid nitrogen

Abstract

The interaction quadrupole-induced dipole correlation function and the corresponding absorption spectrum of liquid nitrogen have been simulated in a site-site molecular dynamics calculation at atmospheric pressure and 66 K. Two models were used: an anisotropic and an isotropic molecular polarizability model. The differences between the two models are significant, but small. The results were compared to the published absorption spectra and reasonable agreement was obtained. The differences between simulation and experiment are discussed in terms of the properties of the model used. The total dipole correlation function was analysed in terms of a self-term and a cross-term. The contribution of the latter, which is negative, is quite large. Furthermore, a number of correlation functions describing the details of the molecular motion in the liquid have been calculated and are discussed in view of a possible discrimination between rotational/translational motions and/or single-molecule/collective motions.