SPC/E model of water

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:

parameter	value
$\sigma$	$3.166{\mathrm {\AA} }$
$\epsilon$	$0.650$ kJ mol-1
$r_{\mathrm {OH} }$	$1.000\mathrm {\AA}$
$\angle _{\mathrm {HOH} }$	$109.47^{\circ }$
$q_{\mathrm {O} }$	$-0.8476e$
$q_{\mathrm {H} }$	$q_{\mathrm {O} }/2$ (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.

• 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

Plastic crystal phases

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

• J. L. Aragones and C. Vega "Plastic crystal phases of simple water models", Journal of Chemical Physics 130 244504 (2009)

Shear viscosity

The shear viscosity for the SPC/E model is 0.729 mPa.s at 298 K and 1 bar (experimental value 0.896 mPa.s ).

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)