regarding pair_style hybrid

Dear lammps users,

We are trying to find out the equilibrated atom positions in a multi atom
type system, with 5 elements, say A,B,C,D and E. Please note that our
target is not to get the exact atom coordinates, but a better
approximation than a random guess. In this context we encountered
following problem.

All the atoms are of metallic type. However we don’t have any eam
potentials for all of the five together. The questions is how to mix the
available potentials so that we can use them in the lammps simulations.

A particular potential available covered elements A-B-C (ternary potential
from NIST website), while another potential covered element D but no
potential available for element E. In this context we thought of using lj
potentials for the element E and all of its cross interactions with others
(it is not a bad approximation as the concentration of E is rather low).

we tried something like this

###For self interactions
pair_style hybrid eam/alloy lj/cut 8.0
pair_coeef 13 13 eam/alloy ABC.eam.alloy A B C NULL NULL
pair_coeef 4 4 eam/alloy ABC.eam.alloy NULL NULL NULL D NULL
pair_coeef 5 5 lj/cut 0.8 1.3

###For cross interactions
pair_coeef 13 4 lj/cut 0.8 1.3
pair_coeef 1
3 5 lj/cut 0.8 1.3
pair_coeef 4 5 lj/cut 0.8 1.3

however lammps complains with following error message

incorrect args for pair coefficients

pair_coeff 5 5 lj/cut 0.8 1.3

Although we developed this coded based on the help from the manual only,
it looks like some silly mistake is happening somewhere. we appreciate
your help in this regard

with best regards


Please read the pair_style eam doc page. The pair coeff

commands for eam/alloy need to be * , not 13 1*3, etc.