Ab-initio study of NMR chemical shifts of water under normal and supercritical conditions.

We present a theoretical investigation of the hydrogen nuclear magnetic resonance (NMR) chemical shift and the magnetic susceptibility of normal and supercritical water using a recently developed ab initio approach in the framework of density functional perturbation theory. The results are in very good agreement with experiment. The shifts can be used to determine whether the atomic configurations, taken from a first principles simulation, give a good description of the system on a microscopic scale. In particular, the hydrogen chemical shifts are very sensitive to the character of the hydrogen bond network, which plays a crucial role in the macroscopic properties of liquid water under normal and supercritical conditions.