Align multiple equations IEEEeqnarray

Question

I am trying to align multiple equations left in a two column environment. The equal signs are aligned properly, but are more centered in the column, rahter than aligned on the left side of the column. Could one help me out with proper alignment? Please excuse me for the messy third line equation, but since I am using a two column environment I had to break this equation line as well.

\documentclass[twoside,twocolumn,9pt]{article}
\usepackage{IEEEtrantools}


\begin{document}

    \begin{IEEEeqnarray}{ll}
    P  &= \sum_{i,j; i<j} \left\{ 4\varepsilon_{ij} \left[ \left( \frac{\epsilon_{ij}}{r_{ij}} \right)^{12} - \left(\frac{\epsilon_{ij}}{r_{ij}} \right)^{6} \right] + \frac{q_{i}q_{j}e^{2}}{r_{ij}} \right\} \nonumber\\
       &+ \sum_{i} k_{b,i} (r_{i} - r_{0,i})^{2} + \sum_{i} k_{\theta,i} (\theta_{i} - \theta_{0,i})^{2}  \nonumber\\
       &+ \sum_{i} \frac{1}{2} \left[ k_{\varsigma_{1},i}(1+cos \varsigma) + k_{\varphi_{2},i}(1+cos \varsigma) + \ldots \right. \nonumber\\
    \left. \quad k_{\varsigma_{3},i}(1+cos \varphi) + k_{\varphi_{4},i}(1+cos \varphi)  \right] 
    \end{IEEEeqnarray}

\end{document}

Thanks for the help.

John.

Answer 1

I'd use rCl for the specification.

\documentclass[twoside,twocolumn]{article}
\usepackage{amsmath}
\usepackage{IEEEtrantools}


\begin{document}

\begin{IEEEeqnarray}{rCl}
P &=& \sum_{\substack{i,j \\ i<j}}
      \biggl\{
        4\varepsilon_{ij} \biggl[
          \left( \frac{\epsilon_{ij}}{r_{ij}} \right)^{\!12} -
          \left(\frac{\epsilon_{ij}}{r_{ij}} \right)^{\!6}
        \biggr]
        + \frac{q_{i}q_{j}e^{2}}{r_{ij}}
      \biggr\}
\nonumber\\
  &+& \sum_{i} k_{b,i} (r_{i} - r_{0,i})^{2} +
      \sum_{i} k_{\theta,i} (\theta_{i} - \theta_{0,i})^{2}
\nonumber\\
  &+& \sum_{i} \frac{1}{2}
      \bigl[ k_{\varsigma_{1},i}(1+\cos \varsigma) +
        k_{\varphi_{2},i}(1+\cos \varsigma)
\nonumber\\
  & &\hphantom{\sum} + k_{\varsigma_{3},i}(1+\cos \varphi) + k_{\varphi_{4},i}(1+\cos \varphi)
     \bigr]
\end{IEEEeqnarray}

\end{document}

Points to note:

1. \substack under the first summation to save horizontal space and get alignment in the subsequent lines

2. sparing use of \left and \right, that make oversized fences

3. \! in the exponents to the large parentheses

4. \cos and not cos

5. a phantom in the last line to achieve better spacing

With align:

\documentclass[twoside,twocolumn]{article}
\usepackage{amsmath}

\begin{document}

\begin{align}
P &= \sum_{\substack{i,j \\ i<j}}
     \biggl\{
       4\varepsilon_{ij} \biggl[
         \left( \frac{\epsilon_{ij}}{r_{ij}} \right)^{\!12} -
         \left(\frac{\epsilon_{ij}}{r_{ij}} \right)^{\!6}
       \biggr]
       + \frac{q_{i}q_{j}e^{2}}{r_{ij}}
     \biggr\}
\nonumber\\
  &+ \sum_{i} k_{b,i} (r_{i} - r_{0,i})^{2} +
     \sum_{i} k_{\theta,i} (\theta_{i} - \theta_{0,i})^{2}
\nonumber\\
  &+ \sum_{i} \frac{1}{2}
     \bigl[ k_{\varsigma_{1},i}(1+\cos \varsigma) +
        k_{\varphi_{2},i}(1+\cos \varsigma)
\nonumber\\
  & \qquad\quad + k_{\varsigma_{3},i}(1+\cos \varphi) + k_{\varphi_{4},i}(1+\cos \varphi)
     \bigr]
\end{align}

\end{document}