Microscopic structure of methanol-water mixtures: Synchrotron X-ray diffraction experiments and molecular dynamics simulations over the entire composition range

Edgar Galicia-Andrés, László Pusztai, László Temleitner, Orest Pizio

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

A new set of synchrotron X-ray diffraction data has been measured for water-methanol mixtures, at ambient temperature and pressure, over the entire composition range (methanol content: 0, 20, 40, 60, 70, 80 and 100%). Molecular Dynamics (MD) computer simulation has been used for the interpretation of diffraction data via calculating the total scattering structure factor from the pair distribution functions in the isothermic-isobaric ensemble. It is found that the combination of either the SPC/E or the TIP4P/Ew water models and the OPLS/AA (all atom) methanol force field yields an at least semi-quantitative agreement with measured structure factors for each composition. Based on this finding, the sets of particle coordinates obtained from MD have been exploited for calculating fine details of the structure in terms of the partial radial distribution functions and angular distributions. It is shown that while angular distributions calculated for the first (predominantly, H-bonded) neighbors around methanol molecules vary significantly with the composition, water-centered distribution hardly change with the alcohol concentration. Analysis of the hydrogen bonding between molecules of both species is performed. It shows that both methanol and water molecules prefer water as hydrogen bonded neighbor.

Original languageEnglish
Pages (from-to)586-595
Number of pages10
JournalJournal of Molecular Liquids
Volume209
DOIs
Publication statusPublished - Jun 20 2015

Keywords

  • Molecular dynamics
  • Structure of water methanol mixtures
  • X-ray diffraction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry
  • Materials Chemistry

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