Hydrogen-bond dynamics of confined water in a nanocage manipulated by terahertz waves

Abstract

Understanding the interplay between hydrogen-bond (Hbond) geometry, network connectivity, and lifetimes is crucial for manipulating confined water dynamics at the nanoscale. In this study, molecular dynamics simulations were performed to investigate water molecules confined in a fullerene cage (C₃₂₀) exposed to external terahertz (THz) electric fields. We identify a distinct relationship among Hbond geometry, network connectivity, and lifetimes. Weak THz fields slightly enhance the geometric order of the Hbond network, resulting in slightly increased Hbond lifetimes without significantly affecting network connectivity. Conversely, strong THz fields severely perturb Hbond structures, significantly shortening Hbond lifetimes and compromising network stability. This perturbation triggers a spatial rearrangement of the confined water into a characteristic double-shell structure. Furthermore, the sensitivity of the confined water response is strongly dependent on occupancy. These findings provide comprehensive insights into THz-driven modulation of nanoscale water dynamics, highlighting pathways for precise, non-contact control in nanofluidic and biological applications.