  The hydrogen-bond (H-bond) network of high-pressure water is investigated by
neural-network-based molecular dynamics (MD) simulations with the
first-principles accuracy. The static structure factors (SSFs) of water at
three densities, i.e., 1, 1.115 and 1.24 g/cm3 are directly evaluated from
512-water MD trajectories, which are in quantitative agreement with the
experiments. We propose a new method to decompose the computed SSF and identify
the changes in SSF with respect to the changes in H-bond structures. We find a
larger water density results in a higher probability for one or two
non-H-bonded water molecules to be inserted into the inner shell, explaining
the changes in the tetrahedrality of water under pressure. We predict that the
structure of the accepting end of water molecules is more easily influenced by
the pressure than the donating end. Our work sheds new light on explaining the
SSF and H-bond properties in related fields.
