SPC/HW model of water

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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. (Eq. 1 in [1]):

\Phi_{i,j}= \left[ \frac{C_{12}}{r_{OO}(i,j)}\right]^{12} - \left[ \frac{C_{6}}{r_{OO}(i,j)}\right]^{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):

Thee site water model.png
parameter value
C_{12}  0.3428 (kJ mol-1) 1/12nm
C_6  0.3712 (kJ mol-1) 1/6nm
r_\mathrm{OH} 1.000 Å
\angle_\mathrm{HOH} 109.47^{\circ}
q_{\mathrm{O}} -0.87 e
q_{\mathrm{H}} q_{\mathrm{O}}/2 (charge neutrality)


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