how to correctly simulate the screw dislocation core in bcc

I'm Yi Wang, previously using the email [email protected]
I'm so sorry, the original post somehow is blank. I had to reply to
show the correct contents, but got same blank result. Then I
searched, it is due to my mail provider, so I changed to this email
address.
Sincerely sorry for duplicated results, could the manager kindly help
me correct the blank post?

hi everyone,

I'm simulating the bcc screw dislocation core structure using the lammps.

The material is bcc-Fe, ab-initio predicts it has a compact core. Also
it was told in papers that the Mendelev type potentials can reproduce
that kind of core structure.(potential 2 in Phil. Mag., 83 3977-3994
(2003))

However, with my scripts, I always get a split core, though it can
reproduce the core structure by Ackland 97 potential.

Could you kindly tell me where to find some detailed tutorial on this?
where I made it wrong?

I attached my scripts. Using a110.in do MS simulation, then
postprocessed by core.f90, then using asymptote script s.asy to draw
the differential displacement map.

I want to use the lammps to built the dislocation dipole, so somehow
the dipole building looks strange in my script, though it should work.
And in the asy script, the final task of scale arrow length with 1/3b
is not performed.

There is also a related problem: the easy core and hard core 1/2<111
dislocation core, do they have energy difference? Is this depending on
potentials?

Thanks in advance!