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

Mohd Moid, Yacov Finkelstein, Raymond Moreh, Prabal K. Maiti

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

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.

Original languageEnglish
Pages (from-to)455-461
Number of pages7
JournalJournal of Physical Chemistry Letters
Volume13
Issue number2
DOIs
StatePublished - 20 Jan 2022

ASJC Scopus subject areas

  • Materials Science (all)
  • Physical and Theoretical Chemistry

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