I wish to type this table in REVTeX; however, the code below does not work for \documentclass{revtex4}. (It does work for the article document class, though.)

\documentclass{revtex4}
\usepackage{array,mathtools,amssymb,booktabs}
\newcolumntype{C}{>{$}c<{$}}
\begin{document}
\begin{tabular}{cCCC}
\toprule
\multicolumn{2}{c}{} & K & H\\\midrule
A & a & 1& 4\\\cmidrule(lr){2-4}
B & b & 2 & 5\\\cmidrule(lr){1-4}
\multicolumn{2}{c}{C}& 3 & 6\\\bottomrule
\end{tabular}
\end{document}
The code is from the source of this page. Thanks to the generous cfr.
\AtBeginDocument{\usepackage{booktabs}}(also removingbooktabsfrom the\usepackageon line 2, of course)? – Paul Gessler Jan 12 '15 at 01:20revtex4's own definition of commands such as\toprule. If this is for submission somewhere requiring the use ofrevtex4, I doubt this is a good idea at all. – cfr Jan 12 '15 at 01:22ptunits so do not have the problem. – David Carlisle Jan 12 '15 at 01:36\topruleetc., right? So loadingbooktabsoverwrites those definitions. – cfr Jan 12 '15 at 02:03> \toprule=macro: ->\hline \hline .– David Carlisle Jan 12 '15 at 02:15