Detection of Anomalous Dynamics for a Single Water Molecule.

Water dynamics is of predominant importance in life, and it plays a critical role in chemical and biological systems. Many studies have reported nonbulk and anomalous dynamics of water molecules; however, a general method to detect the anomalous dynamics is yet to be established. Here, we develop a detection approach for the anomalous dynamics of a water molecule. Using a time series of the dipole vector of a water molecule, our approach achieves single-molecule detection of the anomalous dynamics for all water molecules in the system. Moreover, our approach quantifies the anomalous dynamics of a water molecule, which enables users to compare between different systems. In addition to the applicability, our approach has computational efficiency because it never calculates interactions with any other molecules. Experiments on five different systems of molecular dynamics simulations illustrate that our approach successfully detects the change points of water-molecule dynamics. These results demonstrate that our approach is a useful tool and provides a better understanding of dynamics of water molecules.