Chilling alcohol on the computer: isothermal compressibility and the formation of hydrogen-bond clusters in liquid propan-1-ol

Molecular dynamics simulations have been performed to compute the isothermal compressibility \(\kappa _T\) of liquid propan-1-ol in the temperature range \(200 \le T\le 300\) K. A change in behaviour, from normal (high T) to anomalous (low T), has been identified for \(\kappa _T\) at \(210<T<230\) K. The average number of hydrogen bonds (H–bond) per molecule turns to saturation in the same temperature interval, suggesting the formation of a relatively rigid network. Indeed, simulation results show a strong tendency to form H–bond clusters with distinct boundaries, with the average largest size and width of the size distribution growing upon decreasing temperature, in agreement with previous theoretical and experimental studies. These results also emphasise a connection between the behaviour of \(\kappa _T\) and the formation of nanometric structures.