Microscopic Study of Proton Kinetic Energy Anomaly for Nanoconfined Water

Moid, M and Finkelstein, Y and Moreh, R and Maiti, PK (2020) Microscopic Study of Proton Kinetic Energy Anomaly for Nanoconfined Water. In: Journal of Physical Chemistry B, 124 (1). pp. 190-198.

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Abstract

The reported anomalies of the proton mean kinetic energy, Ke(H), in nanoconfined water, as measured by deep inelastic neutron scattering (DINS), constitute a longstanding problem related to proton dynamics in hydrogen-bonded systems. A considerable number of theoretical attempts to explain these anomalies have failed. The mean vibrational density of states (VDOS) of protons in water nanoconfined inside single wall carbon nanotubes (SWCNTs) is calculated as a function of temperature and SWCNT diameter, DCNT, by classical molecular dynamics (MD) simulation using the TIP4P-2005f water model. The calculated VDOS are utilized for deducing the mean kinetic energy of the water protons, Ke(H), by treating each phonon state as a harmonic oscillator. The calculation depicts a strong confinement effect as reflected in the drop of the value of Ke(H) at 5 K for DCNT < â12 à , while absent for larger diameters. The results also reveal very significant blue and red shifts of the stretching and bending modes, respectively, compared to those in bulk ice, in agreement with experiment.

Item Type:	Journal Article
Publication:	Journal of Physical Chemistry B
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society
Keywords:	Hydrogen bonds; Kinetic energy; Molecular dynamics; Neutron scattering; Red Shift; Single-walled carbon nanotubes (SWCN), Classical molecular dynamics; Deep inelastic neutron scattering; Harmonic oscillators; Hydrogen bonded systems; Microscopic study; Proton kinetic energies; Strong confinement; Vibrational density of state, Kinetics
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	28 Jan 2020 09:04
Last Modified:	28 Jan 2020 09:04
URI:	http://eprints.iisc.ac.in/id/eprint/64421

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