Repulsive shoulder system with attractive well potential

The repulsive shoulder system with attractive well potential (RSS-AW) is given by (Eq. 2 ):

$\Phi _{12}(r)/\epsilon =\left({\frac {\sigma }{r}}\right)^{14}+\lambda _{0}-\lambda _{1}\tanh \left(k_{1}(r-\sigma _{1})\right)+\lambda _{2}\tanh \left(k_{2}(r-\sigma _{2})\right)$

where

• $r:=|\mathbf {r} _{1}-\mathbf {r} _{2}|$
• $\Phi _{12}(r)$ is the intermolecular pair potential between two particles or sites
• $\epsilon$ is the well depth (energy)