Editing SPC/E model of water
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{{Stub-water}} | {{Stub-water}} | ||
The | 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>. | ||
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 </math> | | <math>\sigma</math> || <math> 3.166 {\mathrm {\AA}}</math> | ||
|- | |- | ||
| <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</math> | | <math>r_\mathrm{OH}</math> || <math>1.000\mathrm{\AA}</math> | ||
|- | |- | ||
| <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> | | <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). | The SPC/E model has a [[dipole moment]] of 2.351 D. (Ref. 1 Table I). | ||
==Surface tension== | ==Surface tension== | ||
The [[surface tension]] has been studied for the SPC/E model by Vega and Miguel | The [[surface tension]] has been studied for the SPC/E model by Vega and Miguel. | ||
*[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)] | |||
==Phase diagram== | ==Phase diagram== | ||
[[Image:SPC_E_phase_diagram.png|right|400px]] | [[Image:SPC_E_phase_diagram.png|right|400px]] | ||
===Plastic crystal phases=== | ===Plastic crystal phases=== | ||
Recent simulations have demonstrated the existence of [[Plastic crystals | plastic crystal]] phases for the SPC/E model. | Recent simulations have demonstrated the existence of [[Plastic crystals | plastic crystal]] phases for the SPC/E model. | ||
*[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)] | |||
==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)] | |||
#[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)] | |||
[[category: water]] | [[category: water]] | ||
[[category: models]] | [[category: models]] |