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| The '''simple point charge''' (SPC) model | | {{Stub-water}} |
| <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>
| | The '''simple point charge''' empirical [[models |model]] (SPC) of [[water]]. The molecule is modeled as |
| is an [[water models | empirical model of water]]. The molecule is modelled as
| | a rigid triangle, with parameters |
| 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: | |
| [[Image:Thee_site_water_model.png|center|400px]]
| |
| {| border="1" | | {| border="1" |
| |- | | |- |
| | parameter || value | | | parameter || value |
| |- | | |- |
| | <math>\sigma</math> || <math> 3.166</math>Å | | | <math>\sigma</math> || 3.166<math> {\mathrm {\AA}}</math> |
| |- | | |- |
| | <math>\epsilon</math> || <math>0.650</math> kJ mol<sup>-1</sup> | | | <math>\epsilon</math> || 0.650 kJ mol<math>^{-1}</math> |
| |- | | |- |
| | <math>r_\mathrm{OH}</math> || <math>1.000</math>Å | | | <math>\mathcal{l}</math> || 1.000<math>{\mathrm {\AA}}</math> |
| |- | | |- |
| | <math>\angle_\mathrm{HOH}</math> || <math>109.47^{\circ}</math> | | | <math>\theta</math> || 109.47<math>^{\circ}</math> |
| |- | | |- |
| | <math>q_{\mathrm{O}}</math> || <math>-0.82 e</math> | | | <math>q_\mathrm{O}</math> || -0.82 <math>e</math> |
| |-
| |
| | <math>q_{\mathrm{H}}</math> || <math>|q_{\mathrm{O}}|/2</math> (charge neutrality)
| |
| |} | | |} |
|
| |
|
| The SPC model has a [[dipole moment]] of 2.27 D.
| | |
| ==Surface tension==
| |
| The [[surface tension]] has been studied for the SPC model by Vega and Miguel.
| |
| <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==
| |
| Over the years a number of variants of the SPC model have been published:
| |
| *[[SPC/ε water model | SPC/ε]]
| |
| *[[SPC/A]]
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| *[[SPC/E]]
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| *[[SPC/F]]
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| *[[SPC/F2]]
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| *[[SPC/FP]]
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| *[[SPC/FQ]]
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| *[[SPC/Fw]]
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| *[[SPC/HW]]
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| *[[SPC/L]]
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| *[[SPCP]]
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| *[[SPC-pol]]
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|
| |
|
| ==References== | | ==References== |
| <references/>
| | #H. J. C. Berendsen, J. P. M. Postma, W. F. van Gunsteren and J. Hermans, in: Intermolecular Forces (B. Pullman, ed.), Reidel, Dordrecht, p. 331 (1981). |
| [[category: water]] | | [[category: water]] |
| [[category: models]] | | [[category: models]] |