Pressure-dependent structure of methanol-water mixtures up to 1.2 GPa; Neutron diffraction experiments and molecular dynamics simulations

Temleitner, L.*; Hattori, Takanori   ; Abe, Jun*; Nakajima, Yoichi*; Pusztai, L.*

Total structure factors of per-deuterated methanol and heavy water, CDOD and DO, have been determined across the entire composition range at pressures of up to 1.2 GPa, by neutron diffraction. Largest variations due to increasing pressure were observed below 5 , mostly as shifts of the first and second maxima. Molecular dynamics computer simulations been conducted at the experimental pressures to interpret neutron diffraction results. The peak shifts mentioned above could be qualitatively reproduced by simulations. In order to reveal the influence of changing pressure on the local intermolecular structure, simulated structures have been analyzed in terms of hydrogen bond related partial radial distribution functions and size distributions of hydrogen bonded cyclic entities. Distinct differences between pressure dependent structures of water-rich and methanol-rich composition regions have been revealed.