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  Pressure effects in supercooled water: Comparison between a 2D model of water and experiments for surface water on a protein

Franzese, G., Stokely, K., Chu, X.-q., Kumar, P., Mazza, M. G., Chen, S.-H., et al. (2008). Pressure effects in supercooled water: Comparison between a 2D model of water and experiments for surface water on a protein. Journal of Physics: Condensed Matter, 20(49): 494210. doi:10.1088/0953-8984/20/49/494210.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-002B-2F9F-3 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-002B-2FA0-E
Genre: Journal Article

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 Creators:
Franzese, Giancarlo, Author
Stokely, Kevin, Author
Chu, Xiang-qiang, Author
Kumar, Pradeep, Author
Mazza, Marco G.1, Author              
Chen, Sow-Hsin, Author
Stanley, H. Eugene, Author
Affiliations:
1Group Non-equilibrium soft matter, Department of Dynamics of Complex Fluids, Max Planck Institute for Dynamics and Self-Organization, Max Planck Society, ou_2063308              

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 Abstract: Water’s behavior differs from that of normal fluids, having more than sixty anomalies. Simulations and theories propose that many of these anomalies result from the coexistence of two liquid phases with different densities. Experiments in bulk water confirm the existence of two local arrangements of water molecules with different densities, but, because of inevitable freezing at low temperature T , cannot ascertain whether the two arrangements separate into two phases. To avoid the freezing, new experiments measure the dynamics of water at low T on the surface of proteins, finding a crossover from a non-Arrhenius regime at high T to a regime that is approximately Arrhenius at low T . Motivated by these experiments, Kumar et al (2008 Phys. Rev. Lett. 100, 105701) investigated, by Monte Carlo simulations and mean field calculations on a cell model for water in two dimensions (2D), the relation of the dynamic crossover with the coexistence of two liquid phases. They show that the crossover in the orientational correlation time τ is a consequence of the rearrangement of the hydrogen bonds at low T , and predict that: (i) the dynamic crossover is isochronic, i.e. the value of the crossover time τL is approximately independent of pressure P; (ii) the Arrhenius activation energy EA(P) of the low-T regime decreases upon increasing P; (iii) the temperature T ∗(P) at which τ reaches a fixed macroscopic time τ ∗ τL decreases upon increasing P; in particular, this is true also for the crossover temperature TL(P) at which τ = τL. Here, we compare these predictions with recent quasi-elastic neutron scattering (QENS) experiments performed by Chu et al on hydrated proteins at different values of P. We find that the experiments are consistent with these three predictions.

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Language(s): eng - English
 Dates: 2008-11-12
 Publication Status: Published in print
 Pages: -
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 Rev. Method: -
 Identifiers: DOI: 10.1088/0953-8984/20/49/494210
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Title: Journal of Physics: Condensed Matter
Source Genre: Journal
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Publ. Info: Bristol : IOP Publishing
Pages: 10 Volume / Issue: 20 (49) Sequence Number: 494210 Start / End Page: - Identifier: ISSN: 0953-8984
CoNE: /journals/resource/954928562478