Difference between revisions of "SPC model of water"

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The '''simple point charge''' (SPC) model
 
The '''simple point charge''' (SPC) model
<ref>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)</ref>
+
<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. 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. 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]]
 
[[Image:Thee_site_water_model.png‎|center|400px]]
 
{| border="1"
 
{| border="1"

Revision as of 16:15, 19 November 2010

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 {\mathrm {\AA}}
\epsilon 0.650 kJ mol-1
r_\mathrm{OH} 1.000\mathrm{\AA}
\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

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

Related models

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

References

  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