Electronic density response of liquid water using time-dependent density functional theory

Time-dependent density functional theory is used to compute the linear response of a sample made of 32 periodically replicated water molecules. We study the relaxation effects following two different perturbation schemes, namely a point charge disturbance and a sudden switch of an external electric field. The approach, which is based on the real-time propagation of the time-dependent Kohn-Sham equations, is used for the computation of the response and dielectric functions of configurations equilibrated at 2980.3em0exK. A real-time imaging of the density disturbance with a time resolution of 1.2 attoseconds is obtained.