This occurred because you can’t use two separate EAM potential files for this purpose.
i don't think so. the documentation for pair style eam says, that LAMMPS *does* do the mixing, so only i i and j j parameters need to be provided.
the important missing piece of information (as usual) is the LAMMPS version in use. between september 2016 and june 2017, there has been a bug in pair style eam, that would cancel all mixed
so that is one possible explanation. another possible source of error could be the data file, which is not provided.
I am senior lecturer at Liverpool John Moores University (UK) and would be glad if you could help me with a LAMMPS issue.
I am trying to run a NVT simulation of a Silver-Gold alloy (86000 atoms, 20% of Au) using the respective EAM potentials (universal 3, distributed in the potentials directory of lammps). I know that when we use two different metals combined in an alloy,
the EAM parameters for the alloy are automatically generated by standard mixing rules (the best approach would be to have the alloy-EAM potential already parametrized for the Ag-Au alloy, but I don’t find it). The problem is that, although I begin with a nanoalloy
well centered on a cubic box (18 nm of side) and which shows a clear first RDF peak of Au-Ag at 2.9 Angstroms, after I start the simulation even at low temperature, atoms begin to strongly overlap, until they get as close as 0.1 Angstroms (revealed by the
RDF analysis as well as by visual inspection using VMD of the trajectories file). Also, my simulation finishes normally without any errors. Would it be necessary to use SHAKE to prevent atoms from coming so close during the simulation? Or perhaps the repulsive
part of the EAM potential only works for pure Ag or pure Au nanoparticles? Adopting the same procedure to simulate Au-Pt alloys by combining two different individual EAM potential files works fine…
I am running the calculation on a MacPro (24 logical cores) using mpirun with 24 logical cores and my input is shown below: