Travis-S
commented
7 years ago Commenting here to provide documentation showing how the suggestions from @yuttai would improve things. The attached pdf shows how the original macros behave when called with certain inputs, as well as what the improved commands look like.
In order to match the delimiters, maybe the qm symbols should define like this?
\DeclareOption{qm}{\newcommand{\ip}[2]{\ensuremath{\left\langle{#1}\middle\vert{#2}\right\rangle}}\newcommand{\melem}[3]{\ensuremath{\left\langle{#1}\middle\vert{#2}\middle\vert{#3}\right\rangle}}\newcommand{\expval}[1]{\ensuremath{\left\langle #1 \right\rangle}}\newcommand{\op}[2]{\ensuremath{\left\vert{#1}\middle\rangle\middle\langle{#2}\right\vert}}}