SPC/HW model of water

The SPC/HW model is an SPC model designed for heavy 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, i.e. (Ref. 1 Eq. 1):

${\mathrm{\Phi }}_{i,j}={[\frac{C_{12}}{r_{OO}(i,j)}]}^{12}-{[\frac{C_6}{r_{OO}(i,j)}]}^6+\sum _{\alpha =1}^3\sum _{\beta =1}^3\frac{q_{\alpha }(i)q_{\beta }(j)}{r_{\alpha \beta }(i,j)}$

The parameters are as follows (Ref 1 Table I. Note, in the table the HOH (DOD) angle is given as 109.43 but in the text as 109.47):

parameter	value
$C_{12}$	$0.3428$ (kJ mol-1) 1/12nm
$C_6$	$0.3712$ (kJ mol-1) 1/6nm
$r_{\mathrm{O}\mathrm{H}}$	$1.000\AA$
${\mathrm{\angle }}_{\mathrm{H}\mathrm{O}\mathrm{H}}$	$109.47^{\circ }$
$q_{\mathrm{O}}$	$-0.87e$
$q_{\mathrm{H}}$	$q_{\mathrm{O}}/2$ (charge neutrality)
$r_{\mathrm{O}\mathrm{M}}$	$0$ (charge sits on oxygen)

References

1. J. Raul Grigera "An effective pair potential for heavy water", Journal of Chemical Physics 114 pp. 8064-8067 (2001)