I am trying to simulate a simple atom deposition model using the rebo potential as shown in the script below. The same script already exist in the examples file when I download the lammps, but with the LJ potential. I have two problems with this:
First problem: The substrate atoms suddenly blow up instead of just vibrating in their position. I tried to lower the temperature of the FIX langevin command and the thermo step but the best result I got is unstable atom vibration until step number 50.
Second problem: The deposited atoms do not interact with the substrate atoms. I tried to increase the deposition velocity to a 100 Angstroms/picosecond just to reach the substrate before the blow up that happens after the 50 step, but the deposited atoms just penetrated the substrate and there is no interaction between the atoms to simulate the deposition phenomenon.
I am fairly new to using lammps so I am hoping that these problems are simple. If you could tell me how I can solve these problems or any other issues , i would really appreciate it.
Thank you very much in advance!
boundary p p f
lattice sc 2.0
region box block 0 20 0 20 0 30
create_box 2 box
region substrate block 0 INF INF INF INF 11
create_atoms 1 region substrate
pair_coeff * * CH.rebo C H
mass * 1.0
neigh_modify delay 0
group addatoms type 2
region mobile block 0 20 0 20 5 11
group mobile region mobile
compute add addatoms temp
compute_modify add dynamic/dof yes extra/dof 0
fix 1 addatoms nve
fix 2 mobile langevin 1 1 0.001 587283
fix 3 mobile nve
region slab block 0 20 0 20 16 17
fix 4 addatoms deposit 1000 2 1 12345 region slab near 0.5 vz -100 -100
fix 5 addatoms wall/reflect zhi EDGE
thermo_style custom step atoms temp epair etotal
thermo_modify temp add lost/bond ignore lost warn