SPC/E model of water

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The extended simple point charge model, SPC/E is a slight reparameterisation of the SPC model of water, with a modified value for q_{\mathrm{O}}. 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 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}} -0.8476 e
q_{\mathrm{H}} q_{\mathrm{O}}/2 (charge neutrality)

The SPC/E model has a dipole moment of 2.351 D. (Ref. 1 Table I).

Surface tension

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

Phase diagram

SPC E phase diagram.png

Plastic crystal phases

Recent simulations have demonstrated the existence of plastic crystal phases for the SPC/E model.

References

  1. 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)
  2. 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)