The study of correlations between hydrogen bonding characteristics in liquid, sub- and supercritical methanol. Molecular dynamics simulations and Raman spectroscopy analysis

Molecular dynamics (MD) studies of hydrogen bonding (H-bonding) in liquid, sub- and supercritical methanol have been performed in a wide range of thermodynamic parameters of state, using various potential models and two H-bond criteria. It was shown that there is the universal correlation between the average number of H-bonds per molecule (n(HB)) and the mole fraction of H-bonded molecules (X-HB) for the studied thermodynamic parameters of state. The same feature was observed for the correlations between fractions of molecules forming one (f(1)), two (f(2)), three (f(3)) H-bonds and X-HB. These correlations served to fit experimental Raman spectra of methanol recorded under sub-and supercritical conditions. The advantage of the approach used here is that f(1), f(2), f(3) values have a clear physical meaning and are dependent on the values of state parameters.