I was searching for a better xbar and found an answer here from about 11 years ago:
Can I get a \widebar without using the mathabx package?
I used the abbreviated code and it works fine. However, when I put it in a section heading I get a compiler error. Here is the code I'm using:
\documentclass{amsbook}
\usepackage{amsmath}
\usepackage{mathtools}
\usepackage{amssymb}
%%%%%%%%%%%% Code to make a nicer xbar %%%%%%
\makeatletter
\newcommand*\rel@kern[1]{\kern#1\dimexpr\macc@kerna}
\newcommand*\Xbar[1]{%
\begingroup
\def\mathaccent##1##2{%
\rel@kern{0.8}%
\overline{\rel@kern{-0.8}\macc@nucleus\rel@kern{0.2}}%
\rel@kern{-0.2}%
}%
\macc@depth\@ne
\let\math@bgroup\@empty \let\math@egroup\macc@set@skewchar
\mathsurround\z@ \frozen@everymath{\mathgroup\macc@group\relax}%
\macc@set@skewchar\relax
\let\mathaccentV\macc@nested@a
\macc@nested@a\relax111{#1}%
\endgroup
}
\makeatother
%%%%%%%%%%%%%%% End of Code %%%%%%%%%%%%%%%%
\begin{document}
$\Xbar{X}$
\section{All about $\Xbar{X}$}
\end{document}
The first instance is fine but the one in \section blows up. This is way beyond my skill level -- I've no idea what the code between \makeatletter and \makeatother does so I can't even begin to think about debugging. I don't even know what tags to use for this question.
