Anisotropy of the Proton Kinetic Energy as a Tool for Capturing Structural Transition in Water Confined in a Graphene Nanoslit Pore

Moid, M and Finkelstein, Y and Moreh, R and Maiti, PK (2022) Anisotropy of the Proton Kinetic Energy as a Tool for Capturing Structural Transition in Water Confined in a Graphene Nanoslit Pore. In: Journal of Physical Chemistry Letters . pp. 455-461.

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Abstract

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 200 K, 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. © 2022 American Chemical Society.

Item Type:	Journal Article
Publication:	Journal of Physical Chemistry Letters
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society
Keywords:	Anisotropy; Atoms; Hydrogen bonds; Kinetic energy; Kinetics; Molecular dynamics; Molecules, 2D water; Anisotropy ratio; Cartesian frames; Directional component; Frames of reference; Molecular frame; Nanoslit pores; Proton dynamics; Proton kinetic energies; Structural transitions, Graphene
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	14 Feb 2022 15:39
Last Modified:	14 Feb 2022 15:39
URI:	http://eprints.iisc.ac.in/id/eprint/71347

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