%% 
%%  An UIT Edition example
%% 
%%  Example 10-07-7 on page 214.
%% 
%%  Copyright (C) 2010 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{201.70511pt}
\usepackage[utf8]{inputenc}
\AtBeginDocument{\setlength\parindent{0pt}}
\StartShownPreambleCommands
\usepackage{amsmath}
\StopShownPreambleCommands
\begin{document}
\begin{align*}
\hat H\left(r,R\right)
  &= -\frac{1}{2}\sum\limits_{i=1}^N\nabla_i^2 -\frac{1}{2}\sum\limits_{I=1}^M
      \frac{1}{A_I}\nabla_I^2 +\sum\limits_{i=1}^N\sum\limits_{j>i}^N
      \frac{1}{\left|r_i-r_j\right|}\\
  &\mathrel{\phantom{=}}-\sum\limits_{i=1}^N \sum\limits_{I=1}^M
      \frac{Z_I}{\left|r_i-R_I \right|}+\sum\limits_{I=1}^M \sum\limits_{J>I}^M
      \frac{Z_I ZJ}{\left|R_I-R_J\right|}
\end{align*}
\end{document}