lammps/doc/Eqs/pair_hbond_dreiding.tex

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\begin{eqnarray*}
 E & = & \left[LJ(r) | Morse(r) \right] \qquad \qquad \qquad r < r_{\rm in} \\
   & = & S(r) * \left[LJ(r) | Morse(r) \right] \qquad \qquad r_{\rm in} < r < r_{\rm out} \\
   & = & 0 \qquad \qquad \qquad \qquad \qquad \qquad \qquad r > r_{\rm out} \\
 LJ(r) & = & AR^{-12}-BR^{-10}cos^n\theta=
         \epsilon\left\lbrace 5\left[ \frac{\sigma}{r}\right]^{12}-
         6\left[ \frac{\sigma}{r}\right]^{10}  \right\rbrace cos^n\theta\\
 Morse(r) & = & D_0\left\lbrace \chi^2 - 2\chi\right\rbrace cos^n\theta=
         D_{0}\left\lbrace e^{- 2 \alpha (r - r_0)} - 2 e^{- \alpha (r - r_0)} 
         \right\rbrace cos^n\theta \\
 S(r) & = & \frac{ \left[r_{\rm out}^2 - r^2\right]^2  
   \left[r_{\rm out}^2 + 2r^2 - 3{r_{\rm in}^2}\right]} 
 { \left[r_{\rm out}^2 - {r_{\rm in}}^2\right]^3 }
\end{eqnarray*}
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