Structure of liquid nitromethane: comparison of simulation and diffraction studies.

Simulation (molecular dynamics and Car-Parrinello [Phys. Rev. Lett. 55, 2471 (1985)]) and diffraction (x-ray and neutron) studies on nitromethane are compared aiming at the determination of the liquid structure. Beyond that, the capabilities of the methods to describe liquid structure are discussed. For the studied liquid, the diffraction methods are performing very well in the determination of intramolecular structure, but they do not give detailed structural information on the intermolecular structure. The good agreement between the diffraction experiments and the results of molecular dynamics simulations justifies the use of simulations for the more detailed description of the liquid structure using partial radial distribution functions and orientational correlation functions. Liquid nitromethane is described as a molecular liquid without strong intermolecular interactions such as hydrogen bonding, but with detectable orientational correlations resulting in preferential antiparallel order of the neighboring molecules.