Help with lattice command

Hi All,

I’ve been attempting to construct an alpha quartz crystal using the LAMMPS command ‘lattice’ (see input file below). I’m reasonably confident that I’ve chosen the correct scale, lattice and basis vectors, etc., which I’ve verified using the crystal viewing program VESTA. I’m also using the ‘region’ command to create a parallelpiped with the appropriate shape for this crystal. However, when I look at the structure that is created by this command (at timestep 0), it doesn’t construct the correct structure for this unit cell. For example, most of the structure looks like it should, but a few atoms are displaced or missing. I’ve checked and re-checked the lattice parameters to see if they are correct and, to the best of my knowledge, I’ve found no obvious errors. I do notice that by playing with the box size, I might be able to get closer to the correct structure, but this strategy seems like something that shouldn’t be necessary if I was doing everything correctly.

Any suggestions for what I might be doing incorrectly?

Thanks again,
Vanessa

PS Sorry that this is a repeat of an earlier posting, in which I had forgotten to put anything in the subject field.

input file

Hi, maybe the “create_atoms” command is used wrongly.
I am not sure, just give an advice:
create_atoms 1 box &
basis 1 1 &
basis 2 1 &
basis 3 1
create_atoms 2 box &
basis 4 2 &
basis 5 2 &
basis 6 2 &
basis 7 2 &
basis 8 2 &
basis 9 2