Difference between revisions of "SPC model of water"

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The '''simple point charge''' (SPC) model
 
The '''simple point charge''' (SPC) model
UNIQ3c9329b265030360-ref-00000015-QINU
+
<ref>H. J. C. Berendsen, J. P. M. Postma, W. F. van Gunsteren and J. Hermans, in: Intermolecular Forces (B. Pullman, ed.), Reidel, Dordrecht (1981) p. 331 ISBN 902771326X</ref>
 
is an [[water models | empirical model of water]]. The molecule is modelled as
 
is an [[water models | empirical model of water]]. The molecule is modelled as
 
a rigid isosceles triangle, having charges situated on each of the three atoms. As well as [[Coulomb's law |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. As well as [[Coulomb's law |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
 
|-   
 
|-   
| UNIQ3c9329b265030360-math-00000016-QINU || UNIQ3c9329b265030360-math-00000017-QINU&#8491;
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| <math>\sigma</math> || <math> 3.166</math>&#8491;
 
|-
 
|-
| UNIQ3c9329b265030360-math-00000018-QINU || UNIQ3c9329b265030360-math-00000019-QINU kJ mol<sup>-1</sup>
+
| <math>\epsilon</math> || <math>0.650</math> kJ mol<sup>-1</sup>
 
|-
 
|-
| UNIQ3c9329b265030360-math-0000001A-QINU || UNIQ3c9329b265030360-math-0000001B-QINU&#8491;
+
| <math>r_\mathrm{OH}</math> || <math>1.000</math>&#8491;
 
|-
 
|-
| UNIQ3c9329b265030360-math-0000001C-QINU || UNIQ3c9329b265030360-math-0000001D-QINU
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| <math>\angle_\mathrm{HOH}</math> || <math>109.47^{\circ}</math>
 
|-
 
|-
| UNIQ3c9329b265030360-math-0000001E-QINU ||  UNIQ3c9329b265030360-math-0000001F-QINU
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| <math>q_{\mathrm{O}}</math> ||  <math>-0.82 e</math>
 
|-
 
|-
| UNIQ3c9329b265030360-math-00000020-QINU ||  UNIQ3c9329b265030360-math-00000021-QINU (charge neutrality)
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| <math>q_{\mathrm{H}}</math> ||  <math>|q_{\mathrm{O}}|/2</math> (charge neutrality)
 
|}
 
|}
  
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==Surface tension==
 
==Surface tension==
 
The [[surface tension]] has been studied for the SPC model by Vega and Miguel.
 
The [[surface tension]] has been studied for the SPC model by Vega and Miguel.
UNIQ3c9329b265030360-ref-00000022-QINU
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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>
 
==Related models==
 
==Related models==
 
Over the years a number of variants of the SPC model have been published:
 
Over the years a number of variants of the SPC model have been published:
*[[SPC]]
+
*[[SPC/&epsilon; water model | SPC/&epsilon;]]
 +
*[[SPC/A]]
 
*[[SPC/E]]
 
*[[SPC/E]]
 
*[[SPC/F]]
 
*[[SPC/F]]
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*[[SPC/Fw]]
 
*[[SPC/Fw]]
 
*[[SPC/HW]]
 
*[[SPC/HW]]
 +
*[[SPC/L]]
 
*[[SPCP]]
 
*[[SPCP]]
 
*[[SPC-pol]]
 
*[[SPC-pol]]
 +
 
==References==
 
==References==
UNIQ3c9329b265030360-references-00000023-QINU
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<references/>
 
[[category: water]]
 
[[category: water]]
 
[[category: models]]
 
[[category: models]]

Latest revision as of 15:20, 9 February 2015

The simple point charge (SPC) model [1] is an empirical model of water. The molecule is modelled as a rigid isosceles triangle, having charges situated on each of the three atoms. As well as 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
\epsilon 0.650 kJ mol-1
r_\mathrm{OH} 1.000
\angle_\mathrm{HOH} 109.47^{\circ}
q_{\mathrm{O}} -0.82 e
q_{\mathrm{H}} |q_{\mathrm{O}}|/2 (charge neutrality)

The SPC model has a dipole moment of 2.27 D.

Surface tension[edit]

The surface tension has been studied for the SPC model by Vega and Miguel. [2]

Related models[edit]

Over the years a number of variants of the SPC model have been published:

References[edit]

  1. H. J. C. Berendsen, J. P. M. Postma, W. F. van Gunsteren and J. Hermans, in: Intermolecular Forces (B. Pullman, ed.), Reidel, Dordrecht (1981) p. 331 ISBN 902771326X
  2. 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)