Wide-angle X-ray diffraction and molecular dynamics study of medium-range order in ambient and hot water

Huang, Congcong (författare)

Nordlund, D. (författare)

Bergmann, U. (författare)

McQueen, T. (författare)

Pettersson, Lars G.M. (författare): Stockholms universitet,Fysikum,Kvantkemi

(creator_code:org_t)

Royal Society of Chemistry (RSC), 2011
2011
Engelska.
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 13:44, s. 19997-20007

Relaterad länk:: http://arxiv.org/pdf...; visa fler...; https://urn.kb.se/re...; https://doi.org/10.1...; visa färre...

Abstract Ämnesord

Stäng

We have developed wide-angle X-ray diffraction measurements with high energy-resolution and accuracy to study water structure at three different temperatures (7, 25 and 66 degrees C) under normal pressure. Using a spherically curved Ge crystal an energy resolution better than 15 eV has been achieved which eliminates influence from Compton scattering. The high quality of the data allows for a reliable Fourier transform of the experimental data resolving shell structure out to similar to 12 angstrom, i.e. 5 hydration shells. Large-scale molecular dynamics (MD) simulations using the TIP4P/2005 force-field reproduce excellently the experimental shell-structure in the range 4-12 angstrom although less agreement is seen for the first peak in the intermolecular pair-correlation function (PCF). The Shiratani-Sasai Local Structure Index [J. Chem. Phys. 104, 7671 (1996)] identifies a tetrahedral minority giving the intermediate-range oscillations in the O-O PCF and a disordered majority providing a more featureless background in this range. The current study supports the proposal that the structure of liquid water, even at high temperatures, can be described in terms of a two-state fluctuation model involving local structures related to the high-density and low-density forms of liquid water postulated in the liquid-liquid phase transition hypothesis.

Av författaren/redakt...: Huang, Congcong; Wikfeldt, Thor K ...; Nordlund, D.; Bergmann, U.; McQueen, T.; Sellberg, Jonas; visa fler...; Pettersson, Lars ...; Nilsson, Anders; visa färre...

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