Dear all,
I may have an easy question () for some of you) but I could not find a
valid answer.
There is an example in pair_style hybrid such as the following:
pair_style hybrid lj/cut 2.5 tersoff tersoff
pair_coeff * * tersoff 1 Si.tersoff Si NULL
pair_coeff * * tersoff 2 C.tersoff NULL C
pair_coeff 1 2 lj/cut 1.0 1.5
I am interested to do similar type of simulations but eam/fs such as the
following:
pair_style hybrid lj/cut 3.0 lj/cut 3.0 eam/fs eam/fs eam/fs
pair_coeff * * eam/fs 1 Mg.eam.fs Mg NULL NULL
pair_coeff * * eam/fs 2 Ta.eam.fs NULL Ta NULL
pair_coeff * * eam/fs 3 Fe.eam.fs NULL NULL Fe
pair_coeff 1 2 lj/cut 1.0 1.5
pair_coeff 3 2 lj/cut 2.8 2.5
pair_coeff 1 3 none
Could you please explain me why the latter is not possible?
technically, it should be possible, but there are syntax errors and also
conceptual/scientific problems.
you specify lj/cut twice on the pair style line without identifying which
coefficients belong to which. but also, this is not needed. as a
pairwise-additive potential, lj/cut can handle multiple parameter sets
between different pairs of atom types easily.
also the order of atom types in pair_coeff statements has to be I <= J.
however, you should also consider, that your setup has severe "scientific
issues":
in particular, you should look for an EAM potential, that has all three
elements mixed. with the hybrid setup, you are missing the contributions to
the embedding energy from other atom types so that you model each subsystem
as it it was isolated. surely, that cannot be what you want.
finally, for EAM files you usually need to use metal units, but your lj/cut
parameters are *very* suspicious. where did you find them? they look
axel.
Thank you and best regards,