Do all liquids become strongly correlating at high pressure?

Abstract

We present molecular dynamics simulations studying the influence of pressure on the correlation between the constant-volume thermal equilibrium fluctuations of virial W and potential energy U, focusing on liquids that are not strongly correlating at low pressure, i.e., do not have a WU correlation coefficient above 0.9. The systems studied are the two hydrogen-bonded liquids GROMOS methanol and TIT5P water, the ionic liquid defined by a united-atom model of the 1-butyl-3-methyl-imidazolium nitrate and, for reference, the standard single-component Lennard-Jones liquid. The simulations were performed for pressures varying from 0 GPa to 10 GPa. For all systems studied we find that the virial / potential energy correlation increases with increasing pressure. This suggests that if crystallization is avoided, all liquids become strongly correlating at sufficiently high pressure.