Abstract
In liquid state water molecules form the random and percolated network of hydrogen bonds. In order to understand the collective motion of this network, the local radial distribution function was observed with the molecular dynamics simulation. The molecule alternately goes through the structured period and the destructured period. By comparing with the neutron scattering data it is shown that the cluster of the structured molecules resembles to low-density amorphous (LDA) ice, and the cluster of the destructured molecules resembles to the high-density amorphous (HDA) ice. Simulated liquid water, therefore, is a composite of the LDA-like clusters and the HDA-like clusters. The collective network rearrangement motion at the room temperature can be regarded as a molecular scale precursor of the hypothetical transition between high-density liquid (HDL) water and low-density liquid (LDL) water in the supercooled region.
