TY - JOUR
T1 - Microscopic Study of Proton Kinetic Energy Anomaly for Nanoconfined Water
AU - Moid, Mohd
AU - Finkelstein, Yacov
AU - Moreh, Raymond
AU - Maiti, Prabal K.
N1 - Funding Information:
We thank Prof. Chandan Dasgupta and Dr. Hemant Kumar for useful discussion. We acknowledge the Supercomputer Education and Research Center (SERC), IISc, for the computational facility at SAHASRAT and other machines where most of the simulations were done. We also acknowledge DST, India, for the computational support through TUE-CMS machine, IISc. We thank the DAE, India, and DST, India, for financial support. M.M. acknowledges the Councel of Sceintific and Industrial Research (CSIR), India, for financial support.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2020/1/9
Y1 - 2020/1/9
N2 - 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 < ∼12 Å, 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.
AB - 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 < ∼12 Å, 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.
UR - http://www.scopus.com/inward/record.url?scp=85077647327&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcb.9b08667
DO - 10.1021/acs.jpcb.9b08667
M3 - Article
C2 - 31804825
AN - SCOPUS:85077647327
VL - 124
SP - 190
EP - 198
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 1
ER -