\documentclass[aps,pr,onecolumn,superscriptaddress,noshowpacs,a4paper,15pt]{revtex4}
\pdfoutput=1
\bibliographystyle{apsrev4}
\usepackage{color}
\usepackage{dcolumn} %Align table columns on decimal point
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{graphicx}
\usepackage[pdftex]{hyperref}
\hypersetup{colorlinks=true,citecolor=blue,linkcolor=red,urlcolor=blue}
\usepackage[all]{hypcap}
\newcommand{\red}{\color{red}}
\newcommand{\blue}{\color{blue}}
\definecolor{green}{rgb}{0,0.5,0}
\newcommand{\green}{\color{green}}
\newcommand{\white}{\color{white}}
%\newcommand{\cite}[1]{\hspace{-1 ex} % \nocite{#1}\citenum{#1}}
\thickmuskip=0.5\thickmuskip %shorter spaces in math
%
\begin{document}
%
\begingroup
\Large
\begin{eqnarray*}
  E & = & \frac{1}{2} \sum_i \sum_{j \neq i} V_{ij} \\[15pt]
  V_{ij} & = & {\rm Tap}(r_{ij})\left \{ e^{-\alpha (r_{ij}/\beta -1)} 
               \left [ \epsilon + f(\rho_{ij}) + f(\rho_{ji})\right ] - 
                \frac{1}{1+e^{-d\left [ \left ( r_{ij}/\left (s_R \cdot r^{eff} \right ) \right )-1 \right ]}}
                \cdot \frac{C_6}{r^6_{ij}} \right \}\\[15pt]
  \rho_{ij}^2 & = & r_{ij}^2 - ({\bf r}_{ij} \cdot {\bf n}_i)^2 \\[15pt]
  \rho_{ji}^2 & = & r_{ij}^2 - ({\bf r}_{ij} \cdot {\bf n}_j)^2 \\[15pt]
  f(\rho) & = &  C e^{ -( \rho / \delta )^2 }\\[15pt]
  {\rm Tap}(r_{ij}) & = & 20\left ( \frac{r_{ij}}{R_{cut}} \right )^7 -
                          70\left ( \frac{r_{ij}}{R_{cut}} \right )^6 +
                          84\left ( \frac{r_{ij}}{R_{cut}} \right )^5 -
                          35\left ( \frac{r_{ij}}{R_{cut}} \right )^4 + 1
\end{eqnarray*}
\endgroup
%
\end{document}
%
