Slow dynamics of water under pressure

TL;DR

This study uses molecular dynamics simulations to analyze how water's molecular motion slows down under pressure, revealing behavior consistent with mode-coupling theory and identifying a critical temperature where dynamics appear to diverge.

Contribution

It demonstrates that the slow dynamics of water under pressure align with mode-coupling theory predictions using the SPC/E model.

Findings

Diffusion constant follows power-law behavior near T_c(P).

Dynamics are consistent with transient caging of molecules.

Supports MCT as a framework for understanding water's slow dynamics.

Abstract

We perform lengthy molecular dynamics simulations of the SPC/E model of water to investigate the dynamics under pressure at many temperatures and compare with experimental measurements. We calculate the isochrones of the diffusion constant $D$ and observe power-law behavior of $D$ on lowering temperature with an apparent singularity at a temperature $T_c(P)$, as observed for water. Additional calculations show that the dynamics of the SPC/E model are consistent with slowing down due to the transient caging of molecules, as described by the mode-coupling theory (MCT). This supports the hypothesis that the apparent divergences of dynamic quantities along $T_c(P)$ in water may be associated with ``slowing down'' as described by MCT.