%% 
%%  Example 04-01-9 
%%  Copyright (C) 2016 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{110.31393pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{amsmath,braket}
%StopShownPreambleCommands
\begin{document}
\[
 \Braket{\phi | \frac{\partial^2}{\partial t^2} | \psi}
\]
\[
 \Set{\phi | \frac{\partial^2}{\partial t^2} | \psi}
\]
\end{document}
