Triangular well model

From SklogWiki

The triangular well model is given by

$\Phi_{12}\left( r \right) = \left\{ \begin{array}{ccc} \infty & ; & r \leq \sigma \\ \frac{\epsilon (r/\sigma - \lambda)}{(\lambda -1)} & ; &\sigma < r \leq \lambda \sigma \\ 0 & ; & r > \lambda \sigma \end{array} \right.$

where $Φ 12 (r)$ is the intermolecular pair potential, $r$ is the distance $r := |\mathbf{r}_1 - \mathbf{r}_2|$ , $σ$ is the hard diameter, $ε$ is the well depth and λ > 1.