SPC model of water

The simple point charge (SPC) model is an 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 sites, situated on the oxygen atoms. The parameters are as follows:

parameter	value
$\sigma$	$3.166{\mathrm {\AA} }$
$\epsilon$	$0.650$ kJ mol-1
$r_{\mathrm {OH} }$	$1.000\mathrm {\AA}$
$\angle _{\mathrm {HOH} }$	$109.47^{\circ }$
$q_{\mathrm {O} }$	$-0.82e$
$q_{\mathrm {H} }$	$q_{\mathrm {O} }/2$ (charge neutrality)
$r_{\mathrm {OM} }$	$0$ (charge sits on oxygen)

The SPC model has a dipole moment of 2.27 D.

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, p. 331 (1981).