Local Structural Effects on Intermolecular Vibrations in Liquid Water: The Instantaneous‐Normal‐Mode Analysis

Currently, the designations for the low‐frequency vibrational spectrum of liquid watrer are still diversified. In this paper, the water molecules simulated by the SPC/E model are classified into subensembles, characterized by their local structures, which are specified in two different ways: the geometry of Voronoi polyhedron or the H‐bond configuration. Using the instantaneous normal mode (INM) analysis for these subensembles, we investigate the effects of local structure on the low‐frequency INM spectrum of liquid water. From the contributions of these subensembles to the translational INM spectrum, our results provide insights into the geometric effects of local structure and the H‐bond configuration on intermolecular vibrations in liquid water.