Weeks-Chandler-Andersen chains

The Weeks-Chandler-Andersen chain model consists of units composed of the Weeks-Chandler-Andersen reference system model, i.e. :

$\Phi _{\rm {repulsive}}(r)=\left\{{\begin{array}{ll}\Phi _{\rm {LJ}}(r)+\epsilon &{\rm {if}}\;r<2^{1/6}\sigma \\0&{\rm {if}}\;r\geq 2^{1/6}\sigma \end{array}}\right.$

where $\Phi _{\rm {LJ}}(r)$ represents the Lennard-Jones model.