Partial radial distribution functions of methylene halide molecular liquids

The total scattering structure factors of liquid methylene chloride (CH2Cl2), methylene bromide (CH2Br2) and methylene iodide (CH2I2) have been determined at room temperature and atmospheric pressure by neutron and X-ray diffraction. Experimental data were interpreted by means of the Reverse Monte Carlo structural modelling technique, which provided large particle configurations that were consistent with the measured structure factors. From the models, partial radial distribution functions were calculated directly. Comparison with hard sphere like reference systems showed that a surprisingly large part of the pair correlations can be captured via the simple concept of steric effects (packing fraction and molecular shape).