[lammps-users] Lattice command

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1

Dear Lammps users,

I am currently playing around with creating binary alloys. I am relatively new to using LAMMPS and i was wondering if the following commands are correct in generating an initial structure of NiAl.

lattice custom 2.88 a1 1.0 0.0 0.0 a2 0.0 1.0 0.0 a3 0.0 0.0 1.0 basis 0.0 0.0 0.0 basis 0.5 0.5 0.5

region box block 0 13.8 0 28.8 0 14.23
create_box 2 box

create_atoms 2 box basis 1 1 basis 2 2

I do not have any resources who could help me verify these commands and hence my request to the mailing list.

Thanking you,
RD

2

Dear Lammps users,

I am currently playing around with creating binary alloys. I am
relatively new to using LAMMPS and i was wondering if the following
commands are correct in generating an initial structure of NiAl.

lattice custom 2.88 a1 1.0 0.0 0.0 a2 0.0 1.0 0.0 a3 0.0 0.0 1.0
basis 0.0 0.0 0.0 basis 0.5 0.5 0.5

region box block 0 13.8 0 28.8 0 14.23
create_box 2 box

create_atoms 2 box basis 1 1 basis 2 2

I do not have any resources who could help me verify these commands and
hence my request to the mailing list.

it is _very_ easy to verify this.

you can write the output to a dump file
and visualize the result.

just set some arbitrary potential
(e.g. lj/cut with epsilon set to 0.0)

and do a: run 0

that will write the initial coordinates regardless of
how realistic your potential is, and you can look at them.

cheers,
    axel.

3

This looks reasonable. It seems to be a BCC lattice, alternating between Al and Ni. If you are using a published potential, you can just compare LAMMPS results with published results. Visualization will also work, since presumably you know what the crystal is supposed to look like.

The dimensions in the region command seem wrong, because normally these should be integers, if you want a structure that is a periodic crystal. If the cubic crystal dimensions need to be strained, you can scale a1,a2,a3 appropriately.