Role of Charge Ordering in the Dynamics of Cluster Formation in Associated Liquids

Liquids are archetypes of disordered systems, yet liquidsof polarmolecules are locally more ordered than nonpolar molecules, due tothe Coulomb interaction based charge ordering phenomenon. Hydrogenbonded liquids, such as water or alcohols, for example, representa special type of polar liquids, in that they form labile clusteredlocal structures. For water, in particular, hydrogen bonding and therelated local tetrahedrality, play an important role in the variousattempts to understand this liquid. However, labile structures implydynamics, and it is not clear how it affects the understanding ofthis type of liquids from purely static point of view. Herein, wepropose to reconsider hydrogen bonding as a charge ordering process.This concept allows us to demonstrate the insufficiency of the analysisof the microscopic structure based solely on static pair correlationfunctions, and the need for dynamical correlation functions, bothin real and reciprocal space. The subsequent analysis allows to recoverseveral aspects of our understanding of hydrogen bonded liquids, butfrom the charge order perspective. For water, it confirms the jumprotation picture found recently, and it allows to rationalize thecontradicting pictures that arise when following the interpretationsbased on hydrogen bonding. For alcohols, it allows to understand thedynamical origin of the scattering prepeak, which does not exist forwater, despite the fact that both these liquids have very similarhydroxyl group chain clusters. The concept of charge ordering complementedby the analysis of dynamical correlation functions appear as a promisingway to understand microheterogeneity in complex liquids and mixturesfrom kinetics point of view.

Automated summary

Liquids composed of polar molecules are locally more ordered due to charge ordering phenomenon, particularly in hydrogen bonded liquids such as water or alcohols. Reconsidering hydrogen bonding as a charge ordering process helps to better understand the microscopic structure and dynamics of these liquids.