please notice the second meam file has parameters for Ni, Al, *and* Co. but you
"extract" only Al and Ni from the library. also the naming seems to indicate
that the ordering of the indices in the second file would be Ni = 1, Al = 2, Co = 3.
see below, that there are parameters indexed with 1, 2, and 3. so if you come
across a setting with 3, you get the error.
if you change the pair_coeff command like below, it should work. please note the
order of the elements. you need to confirm this with the publication, that the
parameters were taken from.
(and you may need to redo any calculation where you didn't use Ni Al Co in this
order when extracting the parameters from the library file).
pair_coeff * * libraryNiAlCo.meam Ni Al Co NiAlCo.meam Al Ni
Exactly that. I know it's not super intuitive (and the error message doesn't
really help), but the basic logic of the pair_coeff command is like this:
From $LibraryFile, take the elements of the first list and map them to numerical
indices (1...N), then using these indices and the $MeamFile create an alloy, and
then map these names to LAMMPS atom type indices according to the second list.
Also please confirm that the order of 1,2,3 really is what we just assumed it
is, because there is some style difference between listing the screening
parameters as 'i-j by k' (LAMMPS style) or 'i-k-j'. That mostly depends on the
personal taste of the authors, and may or may not be what you think it is.