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I am using the physics package for braket (Dirac) notation. However, some expressions (such as the braket on the right) automatically rescale in the presence of, say, an operator (such as f hat), while others do not (such as the matrix element on the left).

I think this looks a bit ugly, especially when the equations are inline. Rather than making the matrix element bigger, however, I would like the braket to not automatically rescale, and just stay its "normal" size.

problem

The code is

$$ \mel{m}{\hat{f}}{n} = \braket{\hat{f}m}{n} $$
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  • Welcome to TeX SX! Did you try smashing the operator?
    – Bernard
    Commented Apr 14, 2019 at 12:59
  • @Bernard thank you for your reply. I am not familiar with that macro (or any others really). How would it work in my case? Thank you very much!
    – F Badone
    Commented Apr 14, 2019 at 13:05
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    Try \smash{\braket{\hat{f}m}{n}}. Other than this, you shouldn't use the plain TeX construct $$ ... $$ for displayed equations, as it leads to bad spacing. Use \[ ... \] instead.
    – Bernard
    Commented Apr 14, 2019 at 13:12
  • @Bernard shouldn't it be \braket{\smash{\hat{f}m}{\smash{n}}?
    – Skillmon
    Commented Apr 14, 2019 at 13:22
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    The physics package does automatic resizing, which is normally a bad decision to do.
    – egreg
    Commented Apr 14, 2019 at 15:50

1 Answer 1

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You can use \braket*. Apparently, the author didn't feel the need for specifying explicit size with \big or similar commands, like for \abs, for instance. Too bad.

\documentclass{article}

\usepackage{physics}

\begin{document}

\[
\mel{m}{\hat{f}}{n} = \braket*{\hat{f}m}{n}                           
\]

\end{document}

enter image description here

Don't use $$, see Why is \[ ... \] preferable to $$ ... $$?. I don't recommend physics either.

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