Dislocation-Stacking Fault Interaction

Dear All

I am trying to investigate the interaction of dislocation-stacking fault in FCC metal.
The model is visualized here:


In different articles for interaction of dislocation with other defects mentioned to fix the upper and lower parts, Then, give velocity to the middle part or shear stress with NPT command which all stress components are zero except xy one.

I test this for many inputs but stacking fault disappears or the HCP crystal structure of it change to amorphous and dislocation didn’t move toward the stacking fault.

For first method my input is written bellow:

region lower block INF INF INF 1 INF INF units box
region upper block INF INF 1 INF INF INF units box
group lower region lower
group upper region upper
group boundary union lower upper
group mobile subtract all boundary

velocity upper set 0 0 0 units box
velocity lower set 0 0 0 units box

fix 1 all nvt temp 5 5 0.05

fix 4 upper addforce -1 0.0 0.0
fix 5 upper setforce NULL 0.0 0.0
fix 2 lower addforce 1 0.0 0.0
fix 3 lower setforce NULL 0.0 0.0

For second one it is:

region left block INF -160 INF 8 12 INF units box
region right block 160 INF 8 12 INF INF units box
region up block 25 50 65 INF INF INF units box
region bottom block -35 -10 INF -70 INF INF units box

group left region left
group right region right
group up region up
group bottom region bottom
group boundary union left right up bottom
group mobile subtract all boundary

velocity boundary set 0 0 0 units box

fix 1 mobile npt temp 5 5 1 xy 100 100 1000
fix 2 boundary setforce 0.0 0.0 0.0

Could you please tell me what is the proper way to move dislocation to interact with stacking fault ?

I sincerely apologize for taking your time.


you don't seem to have a problem regarding LAMMPS, but rather an issue
with the physics of your simulation. This mailing list is then not the
good place to discuss about it: consider asking you colleagues or

As a general advice, you should always start a dynamic simulation with a
system that has been already relaxed. It does not seem to be the case here.