Dynamics of hydrogen bonds and vibrational spectral diffusion in liquid methanol from first principles simulations with dispersion corrected density functional

Abstract

The effects of dispersion interactions on the dynamics of hydrogen bonds and vibrational spectral diffusion in liquid methanol are investigated through first principles simulations with a dispersion corrected density functional. Calculations are done at two different temperatures of 300 and 350 K and the results are compared with those of an earlier study where no such dispersion corrections were included. It is found that inclusion of dispersion interactions slightly increases the number of molecules held through non-hydrogen-bonded dispersion interactions in the neighborhood which, in turn, makes the dynamics faster. The inclusion of dispersion corrections gives rise to a faster hydrogen bond dynamics compared to the case when no such dispersion corrections are made. Also, the time scale of vibrational spectral diffusion obtained with the dispersion corrected density functional is found to be in better agreement with experiments.