Zero point energy and the origin of the density maximum in water

Deeney, F.A.; O'Leary, J P

doi:10.1016/j.physleta.2007.10.031

Cited by 9 publications

(9 citation statements)

References 30 publications

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“…Within this hypothesis the maximum of E k at 277.15 K, shown in Fig. 1, may be an indirect manifestation of the competition between zero point energy, E 0 , and thermal fluctuations, which has been proposed as the quantum origin of the density maximum [3]. We notice however that quantum effects are not necessarily required to explain the existence of a maximum of density in water [29].…”

mentioning

confidence: 73%

“…Yet water quantum behavior has received less attention than its classical thermodynamic properties, in spite of the modest cooling needed to evidence quantum effects in water. These have been recently suggested to determine the water density maximum [3] and shown to influence the molecular geometry [4] and in particular the OH bond-length. Quantum effects have also been evidenced in the short time dynamics of protons along the OH bond in supercooled [5] and confined water [6,7,8], by Deep Inelastic Neutron Scattering (DINS) [9] experiments and computer simulations [10,11].…”

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confidence: 99%

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A new water anomaly: The temperature dependence of the proton mean kinetic energy

Flammini

Ricci

Bruni

2009

The Journal of Chemical Physics

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In a recent article [Pietropaolo et al., Phys. Rev. Lett.100, 127802 (2008)] we discussed the results of a deep inelastic neutron scattering experiment aimed at the measure of mean kinetic energy, , and momentum distribution of protons in supercooled water. The observed excess of proton mean kinetic energy, with respect to theoretical predictions and measurements in water stable liquid and solid phases, suggested a possible link between the anomalous temperature dependence of water density and the temperature dependence of . Nevertheless, the limited number of data did not allow a more quantitative description. Here we report on new measurements, above and below the temperature of maximum density and in the supercooled phase. These show two maxima: The first one, in the supercooled phase in the range of 269-272 K, and a second one at 277 K, the temperature of the maximum density of water.

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confidence: 73%

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confidence: 99%

A new water anomaly: The temperature dependence of the proton mean kinetic energy

Flammini

Ricci

Bruni

2009

The Journal of Chemical Physics

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“…Head-Gordon and Rick also showed that classical molecular dynamics simulations lead to an erroneous description of the liquid phase of water, if a water model with an environment of two hydrogen bonds only is applied . The origin of the density maximum in water was recently studied by Deeney and O’Leary . The authors accounted for the density maximum in terms of opposing action of two independent physical processes, one of these processes being a classical expansion/contraction effect and the other being identified as quantum zero-point-energy fluctuations.…”

Section: Introductionmentioning

confidence: 99%

Quantum Cluster Equilibrium Theory Applied in Hydrogen Bond Number Studies of Water. 2. Icebergs in a Two-Dimensional Water Continuum?

Lehmann

Spickermann

Kirchner

2009

J. Chem. Theory Comput.

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With the aid of the quantum cluster equilibrium method, we calculate thermodynamic properties for a new water cluster set containing 2-fold and additional tetrahedrally hydrogen-bonded water molecules on the basis of accurate correlated electronic structure calculations. The addition of clusters with 4-fold coordinated water molecules leads to an improved thermodynamical description of the liquid phase in comparison to experimental values. The comparison of the obtained isobars from the pure 2-fold cluster set with the mixed cluster set shows improved results for the mixed set. Furthermore, the results of the liquid-phase entropy calculation compare excellently with experiment if the mixed cluster set is applied. The calculated populations allow us to determine hydrogen bond numbers, resulting in a temperature-dependent average hydrogen bond number. We observe a decreasing average hydrogen bond number of 2.77 at 274 K to 2.26 at 373 K and a dominance of 75% 2-fold hydrogen-bonded water molecules at room temperature for the mixed cluster set.

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“…1, could be considered, on one side, as a microscopic counterpart of a macroscopic quantity, namely water density, while, on the other side, could be rationalized as an indirect manifestation of the competition between zero-point energy and thermal fluctuations. This competition has been proposed as the quantum origin of the density maximum [36]. We note however, that quantum effects are not necessarily required to explain the existence of a maximum of density in water [37].…”

Section: Bulk Water At Ambient Pressurementioning

confidence: 79%