We have greatly simplified run directory creation in GEOS-Chem Classic 13.0.0 and later versions. You no longer need to download the separate GEOS-Chem Unit Tester repository, but can create run directories from a script in the GEOS-Chem source code itself.
Please see the following sections for more information on how to create run directories for GEOS-Chem Classic simulations:
rundir-registration.rst rundir-fullchem.rst rundir-ch4.rst rundir-files.rst