Structure of liquid methylene chloride: Molecular dynamics simulation compared to diffraction experiments

Molecular dynamics simulation and diffraction (X-ray and neutron) studies are compared on methylene chloride with 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 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 justify the use of simulations for the more detailed description of the liquid structure using partial radial distribution functions and orientational correlation functions. Liquid dichloromethane is described as a molecular liquid without strong intermolecular interactions like hydrogen bonding or halogen-halogen contacts, but with detectable orientational correlations resulting in antiparallel, tail-to-tail orientation of the first nearest neighbours, which is lost very quickly and slight preference of parallel head-to-tail and L-shaped orientation can be detected. On the other hand some orientational correlations between rather distant molecules can also be observed.