Elements order in pair_coeff for MEAM


I just realized that the order of elements of the “library.meam” file in the pair_coeff command for the MEAM potential (same for MEAM/C) is important.
For example, these two commands lead to different results:

pair_coeff      * * library.meam Ca Mg CaMg.meam Ca Mg
pair_coeff      * * library.meam Mg Ca CaMg.meam Ca Mg

However, from the documentation, it seems that only the second set of elements is used to map elements to type.
" The MEAM elements are mapped to LAMMPS atom types by specifying N additional arguments after the 2nd filename in the pair_coeff command, where N is the number of LAMMPS atom types"

I never realized it before, because I was always providing the elements in the right order…

If it is not obvious or if I’m the only one to have it, I can provide a minimum working script.

(lammps version: 17 Jan 2018)