A homebrew formula for Multiwfn.
You can install multiwfn with the following command. It can take quite a while to compile.
brew install --HEAD digital-chemistry-laboratory/multiwfn/multiwfn
To add OpenMP support, use instead
brew tap digital-chemistry-laboratory/multiwfn
brew install --HEAD multiwfn --with-openmp
To upgrade to the latest version, run brew upgrade multiwfn --fetch-HEAD
A copy of settings.ini is installed. To use it, set environment variable Multiwfnpath=${HOMEBREW_PREFIX}/etc/multiwfn. If you want to keep the config file between upgrades, copy it to for example ~/.config/multiwfn/ and point Multiwfnpath there instead.