Annoyingly, when trying to use the IOP journal template with the amsmath package you receive an error saying ! LaTeX Error: Command \equation* already defined. Or name \end... illegal, see p.192 of the manual. which is caused by both amsmath and iopart having a definition for \equation*. This error occurs whether or not you are using \equation*. Not using amsmath makes writing maths so horrific you may as well use Word, but there is a way round; place the following lines before importing the amsmath package: \expandafter\let\csname equation*\endcsname\relax \expandafter\let\csname endequation*\endcsname\relax This removes the \equation* definition from iopart so that there isn't a clash when amsmath is imported. Perfect! Now you can use \align, \eqref, \text , etc. which are not part of the iopart package. I found this solution on stack exchange , but it took quite a while to find. Happy Latexing!
Interesting and useful things that I have found out and want to share.