The pes package defines an environment for easy typesetting og potential energy surface diagrams. The packages has a simple command for adding ground states and transition states. The package is very simple which makes it easy to extend to more specific or advanced uses.
The package is supplied in .dtx format. To unpack the .dtx, run make all.
The package requires LaTeX3 support as provided in the l3kernel and l3packages bundles. Both of these are available on CTAN as ready-to-install .zip files.
The .dtx file has been adapted from Joseph Wright's notes2bib package.