[lammps-users] Simulation box size and boundary condition for different lattice

Hi, everyone,

I am trying to model a system with periodic boundaries. There are two kinds of crystal lattice in my system, like following:

xxxxxxxxxxxxxxxxxxx
uuuuuuuuuuuuuuuuuuu

“x” and “u” have different lattice parameters. I use read_data to import all the information. Now I want to set the left and right boundaries of the box periodic. But I am not sure how large the simulation box should be. Because the two parts have different period. If I put them in one box, the length of box can not be integer multiple of both of their lattice parameters. If I put them in two boxes and give boundary condition such as p s s , I don’t know what will be the period of the model in x direction, the larger box length or different period for different boxes. How can I give boundary condition and set box size for this problem?

Any suggestion would be helpful.

Thanks,

Zhao

You can't create two boxes. You could induce strain in one
of the two lattices and force them to fit into the same box, but
that's about your only option. Periodic is periodic.

Steve