If you are encountering errors like, you may want to check

ERROR: No MEAM parameter file in pair coefficients (../pair_meamc.cpp:243)

When a pair_coeff command using a potential file is specified, LAMMPS looks for the potential file in 2 places. First it looks in the location specified. E.g. if the file is specified as “niu3.eam”, it is looked for in the current working directory. If it is specified as “../potentials/niu3.eam”, then it is looked for in the potentials directory, assuming it is a sister directory of the current working directory. If the file is not found, it is then looked for in one of the directories specified by the LAMMPS_POTENTIALS environment variable. Thus if this is set to the potentials directory in the LAMMPS distribution, then you can use those files from anywhere on your system, without copying them into your working directory. Environment variables are set in different ways for different shells. Here are example settings for

 export LAMMPS_POTENTIALS=/path/to/lammps/potentials

For more information, do read LAMMPS Documentation https://docs.lammps.org/stable/pair_coeff.html