Nonlocal Dielectric Saturation in Liquid Water

Abstract

The linear and nonlinear dielectric response of water to spatially varying electric fields of different wavelength and field strengths is calculated by means of molecular dynamics computer simulation for a central force model of water. We find that nonlinear effects are strongest at $k\approx 3{Å}^{-1\mathrm{}}$, where the linear response function $\chi \left(k\right)=1-1/\epsilon \left(k\right)$ has its main maximum. For small $k$ the response is linear up to field strengths of $E_0\approx 1\mathrm{V}/Å$. A phenomenological theory is discussed which reproduces the main nonlinear effects found in the simulation.