Hello everyone;
I am new user in Lammps. I want to conduct a molecular simulation of physical sputtering yield after successive argon bombardment onto a substrate. However,I could not find any sputtering occur,only diffusion.I am using tersoff brenner potential for silica and lj/cut for Ar-Ar,Ar-Si,Ar-O.Potential for Ar-Si I set to 0 because from literature I read said the interactions of the adsorbed molecules are dominated by dispersive forces between Ar and oxygen,meaning the silicon van der waals interaction are taken into account through an effective potential with only oxygen atoms.

Below is my input file,I really appreciate if anyone can give hint and guidance.

units metal
atom_style atomic
dimension 3
boundary p p f

read_data sio22.data
pair_style hybrid tersoff lj/cut 2.5
pair_coeff * * tersoff SiO.tersoff O Si NULL

pair_coeff 1 3 lj/cut 0.0 1.0
pair_coeff 2 3 lj/cut 0.009285 3.15
pair_coeff 3 3 lj/cut 0.01069699 3.38

neigh_modify delay 0

region slab block -1 1 -1 1 39 40
region fixlayer block INF INF INF INF -INF 3
group addatoms type 3
group fixed region fixlayer

compute add addatoms temp
compute ke addatoms ke/atom
compute_modify add dynamic yes extra 0

fix 1 addatoms nve
fix 2 addatoms deposit 1000 3 10 12345 region slab near 1.0 vz 1.0 4.0
fix 3 fixed momentum 1 linear 1 1 1
#fix 3 addatoms wall/reflect zhi edge

thermo_style custom step atoms temp epair etotal press
thermo 100
thermo_modify lost ignore

dump 1 all atom 5 atom..lammpstrj
#dump KE addatoms custom 1 test_addatoms.
id type xs ys zs c_ke
run 20000

Thank You

Presumably if you send the Ar atoms in at high enough
energy they will knock something loose. Setting the

Ar-Si interaction to 0 does not sound physical. That means those atoms
could pass thru each other.