SPC model of water

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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. [2]

Related models

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


  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)