[Tex/LaTex] bar through letter in mathmode

Question

Hi do you know how I can produce this symbol in latex? Only the bar through the letter i need I know the rest. And i need something that works on math mode for sure. I tried using \sout with ulem package combined with \ddots but didn't work.

\documentclass[12pt]{article} 
\usepackage[margin=1in]{geometry} 
\usepackage{amsmath,amsthm,amssymb,empheq,caption}
\usepackage{graphicx}
\usepackage{siunitx}
\usepackage{mathtools}
\usepackage{float}
\usepackage{ulem}

\begin{document}

   \begin{equation}
     \frac{dJ}{dt}=-\frac{2}{5}\frac{G}{c^5}\epsilon_{ijk}
       \Big\langle{\sout{\ddot{I}_{jm}}\sout{\dddot{I}_{km}}}\Big\rangle
   \end{equation}

\end{document}

Output of the code

Answer 1

Here's a possible solution working in all sizes.

\documentclass{article}
\usepackage{amsmath}
\usepackage{etoolbox}

% fix amsmath's \dddot
\patchcmd{\dddot}{#1}{\kern0pt #1}{}{}

\makeatletter
\DeclareRobustCommand{\barredI}{%
  \mathord{\vphantom{I}\mathpalette\@barredI\relax}%
}

\newcommand{\@barredI}[2]{%
  \ooalign{%
    \hidewidth\@barredIbar#1\hidewidth\cr
    $\m@th#1I$\cr
  }%
}

\newcommand{\@barredIbar}[1]{%
  \check@mathfonts
  \ifx#1\displaystyle
    \fontsize{\f@size}{\z@}%
    \def\@barredIbarkern{0.3}%
  \else
    \ifx#1\textstyle
      \fontsize{\f@size}{\z@}
      \def\@barredIbarkern{0.3}%
    \else
      \ifx#1\scriptstyle
        \fontsize{\sf@size}{\z@}
        \def\@barredIbarkern{0.4}%
      \else
        \fontsize{\ssf@size}{\z@}
        \def\@barredIbarkern{0.47}%
      \fi
    \fi
  \fi
  \usefont{OT1}{cmr}{m}{n}%
  \kern-\@barredIbarkern em 
  \raisebox{-.5ex}{\symbol{'26}}%
}
\makeatother

\begin{document}

$\barredI_{\barredI_{\barredI}}$ $I\barredI$

\bigskip

$\dddot{I}_{\!jk}\dddot{\barredI}_{\!jk}$

\end{document}