LJ and eam/alloy

Dear Lammps users,

In my simulation I have Cu as the main lattice for which eam/alloy is used. Al solute atoms are located in the Cu lattice. I am going to use LJ potential to define the interaction between Al-Al and Al-Cu atoms.

the followings are the command lines:

pair_style eam/alloy
pair_coeff * * Cu01.eam.alloy Cu Cu

pair_style lj/cut 8.0
pair_coeff 1 2 0.40041 2.479

pair_style lj/cut 8.0
pair_coeff 2 2 0.392 2.620

When I use these commands, lammps gives me this error “All pair coeffs are not set”. I can fix this error by adding

pair_style lj/cut 8.0
pair_coeff 1 1 0.409 2.338

to the code. These lines define the Cu-Cu LJ parameters. As I have already used eam/alloy for Cu-Cu interactions, does adding these lines make any problem? If so, how can I fix this problem without adding these commands?

Thanks,
Iman.

Dear Lammps users,
In my simulation I have Cu as the main lattice for which eam/alloy is
used. Al solute atoms are located in the Cu lattice. I am going to use LJ
potential to define the interaction between Al-Al and Al-Cu atoms.

why that? why not find/generate a CuAl alloy eam potential file?
e.g. the program in tools/eam_database supports this mixture.

the followings are the command lines:
pair_style eam/alloy
pair_coeff * * Cu01.eam.alloy Cu Cu
pair_style lj/cut 8.0
pair_coeff 1 2 0.40041 2.479
pair_style lj/cut 8.0
pair_coeff 2 2 0.392 2.620
When I use these commands, lammps gives me this error "All pair coeffs are
not set". I can fix this error by adding
pair_style lj/cut 8.0
pair_coeff 1 1 0.409 2.338
to the code. These lines define the Cu-Cu LJ parameters. As I have already
used eam/alloy for Cu-Cu interactions, does adding these lines make any

no, you _don't_ have the eam/alloy parameters anymore.
_every_ pair_style command overrides the previous one
and eliminates all existing pair_coeff flags. please read
the lammps documentation more carefully. it is explained
in detail. if you want to mix and match multiple pair styles
in the same calculation, you _have_ to use a hybrid pairstyle
and then set up the corresponding pair coeffs accordingly
(which is a little bit different from the normal input).

problem? If so, how can I fix this problem without adding these commands?

RTFM!

axel.