# caption of the wide table not wide

I am using this code to produce a wide table, but the caption in top is still in two column format.I used \caption package but it affects all of my figures captions and never solve the problem.

    \documentclass[prb,twocolumn,preprintnumbers,amsmath,amssymb]{revtex4}
\usepackage{graphicx}
\usepackage{booktabs}
\usepackage{enumitem}
\usepackage{tabularx}
\usepackage{epsfig}
\usepackage{amsmath,amscd}
\usepackage{psfrag}
\setlength\paperheight{11in}
\usepackage[dvipdfm]{hyperref}
\usepackage{amsmath,amscd}
\usepackage{psfrag}

\begin{table}[p]
\caption{Plots of average power dissipated $\overline P$ vs the amplitude of second         harmonic $H_{ac2}$ for different values of the relative phase $\theta$, while $m=3$,  $\alpha=0.05$ and $H_{ac1}=2 H_1$.}
\centering
\begin{tabularx}{\textwidth}{|X|X|X|}
\multicolumn{3}{>{\centering\setlength\hsize{3\hsize} }X}{\boldmath$m=3$\unboldmath   ,       \boldmath$\alpha=0.05$\unboldmath , \boldmath$H_{ac1}=2H_1$\unboldmath}\\ \hline
\includegraphics[height=1.7 in,width=2.3 in]{t21.eps} & \includegraphics[height=1.7 in,width=2.3 in]{t22.eps} & \includegraphics[height=1.7 in,width=2.3 in]{t23.eps}\\ \hline
\includegraphics[height=1.7 in,width=2.3 in]{t24.eps} & \includegraphics[height=1.7 in,width=2.3 in]{t25.eps} & \includegraphics[height=1.7 in,width=2.3 in]{t26.eps}\\ \hline
\end{tabularx}
\end{table}

-
Not directly related to your main question, but possibly of some use for improving the code and the look of the table: (i) Since you're setting the width of the tabularx environment to \textwidth, there's no point in specifying \centering. (ii) You can probably dispense with the \hline instructions as well as the vertical bars that separate the cells, i.e., I'd write \begin{tabularx}{\textwidth}{@{}XXX@{}}. –  Mico Mar 12 '14 at 13:12

In a twocolumn text the table (and figure) environment only covers one column by default. The starred versions, table* and figure* cover both columns, so you want
\begin{table*}