Structural and dynamic anomalous properties of TIP4P/2005 water at extreme pressures

Abstract

Water shows numerous thermodynamic, dynamic, and structural anomalies. Recent experiments [Eichler et al., Phys. Rev. Lett. 134, 134101 (2025)], based on measurements of shear and bulk viscosities of liquid water up to 1.6 GPa, have reported the existence of a minimum in the variation of the structural relaxation time τα with pressure at room temperature. Here, we investigate this and related properties with molecular dynamics simulations of the TIP4P/2005 water model, performed at extreme pressures commensurate with the experiments. Specifically, we compute dynamic (self-diffusion, shear and bulk viscosities, and structural relaxation time) and structural (oxygen–oxygen radial distribution function, structure factor, and translational order parameter) properties down to 220 K and up to 2.7 GPa. We find good agreement with the experimental observations and confirm the existence of a minimum in τα. The microscopic information obtained from the simulations suggests that this anomaly is related to the sudden reorganization of the hydrogen bond network induced by pressurization.