Hard core Yukawa potential

Hard core attractive Yukawa potential:

$V\left(r\right)=\left\{{\begin{array}{lll}\infty &;&r<\sigma \\-\left({\frac {\epsilon \sigma }{r}}\right)\exp \left[-\kappa \left({\frac {r}{\sigma }}-1\right)\right]&;&r\geq \sigma \end{array}}\right.$

where $V\left(r\right)$ is the potential energy of interaction between pairs of particles, $r$ is the distance, $\sigma$ is the hard diameter, $\epsilon$ is the energy well depth ($\epsilon >0$), and $\kappa$ is a parameter that controls the interaction range ($\kappa >0$).