dviktor [1] filed a deletion request for plumed-namd [2]:

This and charm++-mpi packages were created for small group of scientists in Moscow State University as temporary solution for current work. They are highly tuned for our needs and are of little value for other users. Now we've created our local repo with different versions so we've decided to request deletion of them from AUR

[1] https://aur.archlinux.org/account/dviktor/ [2] https://aur.archlinux.org/pkgbase/plumed-namd/