mW model of water

The mW model ^[1] 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}\Phi _{ij}(r_{ij})+\sum _{i}\sum _{j\neq i}\sum _{k>j}\Phi _{ijk}(r_{ij},r_{ik},\theta _{ijk})

where

\Phi _{ij}(r_{ij})=A\epsilon \left[B\left({\frac {\sigma }{r}}\right)^{p}-\left({\frac {\sigma }{r}}\right)^{q}\right]\exp \left({\frac {\sigma }{r-a\sigma }}\right)

and

\Phi _{ijk}(r_{ij},s_{ik},\theta _{ijk})=\lambda \epsilon \left[\cos \theta -\cos \theta _{0}\right]^{2}\exp \left({\frac {\gamma \sigma }{r-a\sigma }}\right)\exp \left({\frac {\gamma \sigma }{s-a\sigma }}\right)

where

$A=7.049556277$ , $B=0.6022245584$ , $p=4$ , $q=0$ , and Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \gamma = 1.2}