Difference between revisions of "SPC/E model of water"

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{{Stub-water}}
 
{{Stub-water}}
The extended simple point charge model, '''SPC/E''' is a slight reparameterisation  of the [[SPC]] model of [[water]], with a modified value for <math>q_{\mathrm{O}}</math>.
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The '''SPC/E''' (extended simple point charge model) <ref>[http://dx.doi.org/10.1021/j100308a038  H. J. C. Berendsen, J. R. Grigera, and T. P. Straatsma "The missing term in effective pair potentials", Journal of Physical Chemistry '''91''' pp. 6269 - 6271 (1987)]</ref>
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<ref>[http://dx.doi.org/10.1063/1.2841127 Swaroop Chatterjee, Pablo G. Debenedetti, Frank H. Stillinger, and Ruth M. Lynden-Bell "A computational investigation of thermodynamics, structure, dynamics and solvation behavior in modified water models", Journal of Chemical Physics '''128''' 124511 (2008)]</ref> is a slight reparameterisation  of the [[SPC]] model of [[water]], with a modified value for <math>q_{\mathrm{O}}</math>.
 
The molecule is modelled as
 
The molecule is modelled as
 
a rigid isosceles triangle, having charges situated on each of the three atoms. Apart from Coulombic interactions, the molecules interact via long-range [[Lennard-Jones model | Lennard-Jones]] sites, situated  on the  oxygen atoms. The parameters are as follows:
 
a rigid isosceles triangle, having charges situated on each of the three atoms. Apart from Coulombic interactions, the molecules interact via long-range [[Lennard-Jones model | Lennard-Jones]] sites, situated  on the  oxygen atoms. The parameters are as follows:
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| parameter || value
 
| parameter || value
 
|-   
 
|-   
| <math>\sigma</math> || <math> 3.166 {\mathrm {\AA}}</math>
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| <math>\sigma</math> || <math> 3.166 </math> &Aring;
 
|-
 
|-
 
| <math>\epsilon</math> || <math>0.650</math> kJ mol<sup>-1</sup>
 
| <math>\epsilon</math> || <math>0.650</math> kJ mol<sup>-1</sup>
 
|-
 
|-
| <math>r_\mathrm{OH}</math> || <math>1.000\mathrm{\AA}</math>
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| <math>r_\mathrm{OH}</math> || <math>1.000</math> &Aring;
 
|-
 
|-
 
| <math>\angle_\mathrm{HOH}</math> || <math>109.47^{\circ}</math>
 
| <math>\angle_\mathrm{HOH}</math> || <math>109.47^{\circ}</math>
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| <math>q_{\mathrm{O}}</math> ||  <math>-0.8476 e</math>
 
| <math>q_{\mathrm{O}}</math> ||  <math>-0.8476 e</math>
 
|-
 
|-
| <math>q_{\mathrm{H}}</math> ||  <math>q_{\mathrm{O}}/2</math> (charge neutrality)
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| <math>q_{\mathrm{H}}</math> ||  <math>|q_{\mathrm{O}}|/2</math> (charge neutrality)
 
|}
 
|}
The SPC/E model has a [[dipole moment]] of 2.351 D. (Ref. 1 Table I),
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The SPC/E model has a [[dipole moment]] of 2.351 D. (Ref. 1 Table I).
 +
==Surface tension==
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The [[surface tension]] has been studied for the SPC/E model by Vega and Miguel
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<ref>[http://dx.doi.org/10.1063/1.2715577 C. Vega and E. de Miguel "Surface tension of the most popular models of water by using the test-area simulation method", Journal of Chemical Physics '''126''' 154707 (2007)]</ref>
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==Phase diagram==
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[[Image:SPC_E_phase_diagram.png|right|400px]]
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===Plastic crystal phases===
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Recent simulations have demonstrated the existence of  [[Plastic crystals | plastic crystal]] phases for the SPC/E model.
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<ref>[http://dx.doi.org/10.1063/1.3156856  J. L. Aragones and C. Vega "Plastic crystal phases of simple water models", Journal of Chemical Physics '''130''' 244504 (2009)]</ref>
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==Shear viscosity==
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The [[shear viscosity]] for the SPC/E model is 0.729 mPa.s at 298 K and 1 bar <ref>[http://dx.doi.org/10.1063/1.3330544 Miguel Angel González and José L. F. Abascal "The shear viscosity of rigid water models", Journal of Chemical Physics '''132''' 096101 (2010)]</ref> (experimental value 0.896  mPa.s <ref>[http://dx.doi.org/10.1021/je049918m Kenneth R. Harris and Lawrence A. Woolf "Temperature and Volume Dependence of the Viscosity of Water and Heavy Water at Low Temperatures", Journal of Chemical & Engineering Data '''49''' pp. 1064-1069 (2004)]</ref>).
 +
 
 +
==Thermal conductivity==
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[[Thermal conductivity]] <ref>[http://dx.doi.org/10.1063/1.4739855  Frank Römer, Anders Lervik, and Fernando Bresme "Nonequilibrium molecular dynamics simulations of the thermal conductivity of water: A systematic investigation of the SPC/E and TIP4P/2005 models", Journal of Chemical Physics '''137''' 074503 (2012)]</ref>.
 +
 
 
==References==
 
==References==
#[http://dx.doi.org/10.1021/j100308a038  H. J. C. Berendsen, J. R. Grigera, and T. P. Straatsma "The missing term in effective pair potentials", Journal of Physical Chemistry '''91''' pp. 6269 - 6271 (1987)]
+
<references/>
#[http://dx.doi.org/10.1063/1.2841127 Swaroop Chatterjee, Pablo G. Debenedetti, Frank H. Stillinger, and Ruth M. Lynden-Bell "A computational investigation of thermodynamics, structure, dynamics and solvation behavior in modified water models", Journal of Chemical Physics '''128''' 124511 (2008)]
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;Related reading
 +
*[http://dx.doi.org/10.1063/1.3548869  Péter T. Kiss and András Baranyai "Sources of the deficiencies in the popular SPC/E and TIP3P models of water", Journal of Chemical Physics '''134''' 054106 (2011)]
 
[[category: water]]
 
[[category: water]]
 
[[category: models]]
 
[[category: models]]

Latest revision as of 14:30, 4 February 2015

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The SPC/E (extended simple point charge model) [1] [2] is a slight reparameterisation of the SPC model of water, with a modified value for q_{\mathrm{O}}. The molecule is modelled as a rigid isosceles triangle, having charges situated on each of the three atoms. Apart from Coulombic interactions, the molecules interact via long-range Lennard-Jones sites, situated on the oxygen atoms. The parameters are as follows:

Thee site water model.png
parameter value
\sigma  3.166 Å
\epsilon 0.650 kJ mol-1
r_\mathrm{OH} 1.000 Å
\angle_\mathrm{HOH} 109.47^{\circ}
q_{\mathrm{O}} -0.8476 e
q_{\mathrm{H}} |q_{\mathrm{O}}|/2 (charge neutrality)

The SPC/E model has a dipole moment of 2.351 D. (Ref. 1 Table I).

Surface tension[edit]

The surface tension has been studied for the SPC/E model by Vega and Miguel [3]

Phase diagram[edit]

SPC E phase diagram.png

Plastic crystal phases[edit]

Recent simulations have demonstrated the existence of plastic crystal phases for the SPC/E model. [4]

Shear viscosity[edit]

The shear viscosity for the SPC/E model is 0.729 mPa.s at 298 K and 1 bar [5] (experimental value 0.896 mPa.s [6]).

Thermal conductivity[edit]

Thermal conductivity [7].

References[edit]

Related reading