Nanometer range correlations between molecular orientations in liquids of molecules with perfect tetrahedral shape:...

Neutron and x-ray weighted total scattering structure factors of liquid carbon, silicon, germanium, and tin tetrachlorides, CCl(4), SiCl(4), GeCl(4), and SnCl(4), have been interpreted by means of reverse Monte Carlo modeling. For each material the two sets of diffraction data were modeled simultaneously, thus providing sets of particle coordinates that were consistent with two experimental structure factors within errors. From these particle configurations, partial radial distribution functions, as well as correlation functions characterizing mutual orientations of molecules as a function of distance between molecular centers were calculated. Via comparison with reference systems, obtained by hard sphere Monte Carlo simulations, we demonstrate that orientational correlations characterizing these liquids are much longer ranged than expected, particularly in carbon tetrachloride.