mW model of water

The mW model of water is an atom with tetrahedrality intermediate between carbon and silicon. mW mimics the hydrogen-bonded structure of water through the introduction of a nonbond angular dependent term that encourages tetrahedral configurations. The model is given by:

$E={\sum }_i{\sum }_{j>i}{\mathrm{\Phi }}_{ij}(r_{ij})+{\sum }_i{\sum }_{j\ne i}{\sum }_{k>j}{\mathrm{\Phi }}_{ijk}(r_{ij},r_{ik},{\theta }_{ijk})$

where

${\mathrm{\Phi }}_{ij}(r_{ij})=Aϵ[B{(\frac{\sigma }{r})}^p-{(\frac{\sigma }{r})}^q]\exp (\frac{\sigma }{r-a\sigma })$

and

${\mathrm{\Phi }}_{ijk}(r_{ij},s_{ik},{\theta }_{ijk})=\lambda ϵ{[\cos \theta -\cos {\theta }_0]}^2\exp (\frac{\gamma \sigma }{r-a\sigma })\exp (\frac{\gamma \sigma }{s-a\sigma })$

where

$A=7.049556277$, $B=0.6022245584$, $p=4$, $q=0$, and $\gamma =1.2$

References

Related reading

• Emily B. Moore and Valeria Molinero "Ice crystallization in water’s “no-man’s land”", Journal of Chemical Physics 132, 244504 (2010)