Penetrable sphere model
From SklogWiki
The penetrable sphere model is given by
\[ \Phi_{12}\left( r \right) = \left\{ \begin{array}{ccc} \epsilon & ; & r < \sigma \\ 0 & ; & r \ge \sigma \end{array} \right. \]
where \(\Phi_{12}(r)\) is the intermolecular pair potential, \(\epsilon\) is the hight of the repulsive core, \(r\) is the distance between site 1 and site 2 \(r := |\mathbf{r}_1 - \mathbf{r}_2|\) and \(\sigma\) is the radius of the core. Note: an earlier, different, penetrable sphere model was proposed, but is now known as the Widom-Rowlinson model. This model can be seen as the limiting case of the Gaussian overlap model where \(n \rightarrow \infty\).
