Dynamics and hydrogen bonding in liquid ethanol

Molecular dynamics simulations of liquid ethanol at three temperatures have been carried out. The hydrogen bonding states of ethanol molecules have be en characterized by the number of hydrogen bonds in which the molecules par ticipate. It is observed that the mean lifetimes of molecules in each hydro gen bonding state are markedly dependent on the temperature. Moreover, mole cules with one hydrogen bond are more stable when they are donors than when they are accepters. The dependence of the reorientational correlation func tions on the hydrogen bonding state of molecules has been studied carefully . The decay of these functions is slower for molecules with higher numbers of hydrogen bonds and also becomes slower as temperature decreases. The rel axation for molecules with only one hydrogen bond is faster for those actin g as proton donors than for those acting as proton accepters. Finally, the results obtained by computer simulation are compared with those from recent measurements of the frequency-dependent dielectric permittivity of liquid ethanol.