Soft-core square well model

The soft-core square well model is given by

$\Phi _{12}\left(r\right)=\left\{{\begin{array}{lcc}4\epsilon \left[\left({\frac {\sigma }{r}}\right)^{n}-\left({\frac {\sigma }{r}}\right)^{n/2}\right]&;&r\leq r_{m}\\-\epsilon &;&r_{m}<r\leq \lambda \sigma \\0&;&r>\lambda \sigma \end{array}}\right.$

where 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 \Phi_{12}(r)} is the intermolecular pair potential, 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 r_m = 2^{2/n}\sigma} , 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 \epsilon} is the well depth, 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 r} is the distance, σ is the hard diameter and λ > 1.

References

1. Mohammad Shokouhi and Gholam Abbas Parsafar "The effect of steepness of soft-core square-well potential model on some fluid properties", Molecular Physics 106 pp. 103-112 (2008)