I am facing some problem with the displace_atoms command.
In few words, I work on bcc Fe crystal (ppp conditions). I am testing the voronoi/atom compute to see if I am able to identify vacancies and interstitials. That works fine, I understood how to locate them. However, during some tests I was performing, I observed some unexpected behavior of the displace_atoms command.
In order to test voronoi, what I do is simple, I select an atom from the lattice and I displace it. This way I know when I create a vacancy and an interstitial.
I proceed as follows:
region PKA block (v_xPKA-v_delta) (v_xPKA+v_delta) (v_yPKA-v_delta) (v_yPKA+v_delta) (v_zPKA-v_delta) (v_zPKA+v_delta)
group PKA region PKA
displace_atoms PKA move 1.0 1.0 1.0 units box
write_dump all xyz coord_atoms.xyz
where xPKA, yPKA… are variable defined elsewhere.
What I observe is that sometimes, in the place where there should be no atom (because I displaced it), there is one. However, owing to the voronoi, I find that there is a vacancy just where the atom was displaced, which is what is expected.
So it is contradictory, there is a vacancy and a lattice atom at the same place.
But it is not always like this. Sometimes it works well and we can see that the atom has indeed moved and there is a vacancy in its place.
Is it a bug of the displace_atoms command or is there something that I am missing ?
Could anyone help me please ?
With best regards,