documentation

"colloid (go)"_pair_colloid.html,

"comb (o)"_pair_comb.html,

"comb3"_pair_comb.html,

"cosine/squared"_pair_cosine_squared.html,

"coul/cut (gko)"_pair_coul.html,

"coul/cut/soft (o)"_pair_fep_soft.html,

"coul/debye (gko)"_pair_coul.html,

\documentclass[12pt]{article}

\usepackage{amsmath}

\begin{document}

\begin{align*}

E = 

\begin{cases}

-\epsilon& \quad r < \sigma \\

-\epsilon\cos\left(\frac{\pi\left(r - \sigma\right)}{2\left(r_c - \sigma\right)}\right)&\quad \sigma \leq r < r_c \\

0& \quad r \geq r_c

\end{cases}

\end{align*}

\end{document}

\documentstyle[12pt]{article}

\begin{document}

$$

 E = \epsilon \left[ \left(\frac{\sigma}{r}\right)^{12} - 

                       2\left(\frac{\sigma}{r}\right)^6 + 1\right]

                       , \quad r < \sigma

$$

\end{document}