Anisotropy of the proton kinetic energy as a tool for capturing structural transition in nanoconfined H\(_2\)O

The proton dynamics of a 2D water monolayer confined inside a graphene slit pore is studied in Cartesian and molecular frames of reference using molecular dynamics simulations. The vibrational density of states of the proton was calculated versus temperature and was further used to deduce the mean k...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2021-09
Main Authors: Moid, Mohd, Finkelstein, Yacov, Moreh, Raymond, Maiti, Prabal K
Format: Article
Language:English
Subjects:
Anisotropy
Cartesian coordinates
Chemical bonds
Dynamic structural analysis
Enthalpy
Graphene
Hydrogen atoms
Hydrogen bonds
Hydrogen-based energy
Kinetic energy
Mathematical analysis
Molecular dynamics
Order parameters
Order-disorder transformations
Protons
Temperature effects
Water chemistry
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The proton dynamics of a 2D water monolayer confined inside a graphene slit pore is studied in Cartesian and molecular frames of reference using molecular dynamics simulations. The vibrational density of states of the proton was calculated versus temperature and was further used to deduce the mean kinetic energy of the hydrogen atoms, Ke(H), in both frames of reference. The directional components of Ke(H) are in good agreement with experimental observations for bulk as well as nanoconfined water. Nonetheless, while in the molecular frame of reference the effect of temperature on the anisotropy ratios of Ke(H) (the ratio between its directional components) are practically invariant between the 2D and 3D cases, those in the Cartesian frame of reference reveal a rather notable reduction across 200K, indicating the occurrence of an order-disorder transition. This result is further supported by the calculated entropy and enthalpy of the confined water molecules. Overall it is shown that Ke(H) anisotropy ratios may serve as a valuable order parameter for detecting structural transformations in hydrogen bonds containing molecular systems.
ISSN:2331-8422