The complex dynamics of liquid water are manifested in its unique dielectric relaxation and nonlinear shear rheology. We investigate the dielectric and rheological responses of TIP4P/$\varepsilon$ water using molecular dynamics simulations across a wide temperature range, including the deeply supercooled regime. We demonstrate that the fast secondary Debye relaxation is faithfully captured by the continuous, history-dependent hydrogen-bond lifetime, ${\tau }_{\text{HB}}$, which directly accounts for the high-frequency deviation of the dielectric loss, ${\varepsilon }^{\prime \prime }\left(\omega \right)$, from classical Debye behavior. Unlike the history-independent intermittent lifetime ${\widehat{\tau }}_{\text{HB}}$, which scales linearly with the primary relaxation time ${\tau }_1$ and the $\alpha$-relaxation time ${\tau }_{\alpha }$, the lifetime ${\tau }_{\text{HB}}$ exhibits a distinct nonlinear dependence that characterizes the local kinetic rupture of individual bonds. We establish a link between dielectric relaxation and shear thinning, revealing that the onset of thinning occurs at a critical shear rate ${\dot{\gamma }}_0\lesssim 1/{\tau }_1\sim 1/{\tau }_{\alpha }$, governed by the competition between the shear deformation and the slowest mode of structural relaxation. Furthermore, we explore the impact of ionic solutes on the primary relaxation time ${\tau }_1$ in NaCl solutions. We find that ${\tau }_1$ exhibits a nonmonotonic dependence on salt concentration, reflecting a competition between the disruption of bulk hydrogen bonds and the formation of rigid hydration shells. Our study elucidates the connection between hydrogen bonding, dielectric relaxation, and shear rheology, providing insights applicable to other tetrahedral liquids.

Close

PrevNext

Reuse & PermissionsView figure in article

• 
• 
• 
• 

• Dielectric properties
• Hydrogen bonds
• Shear flows
• Supercooled liquid
• Water
• Shear thinning
• Molecular dynamics