Collision Cascade simulation in Tungsten

Dear all

I am trying to simulate a collision cascade in tungsten, but unfortunately, it is happening the following problem:

I am giving the energy to an atom, so far everything it is fine. When this atom approaches of a second one it is possible to observe the potential energy increasing (because of proximity between the two atoms); however, the kinect energy does not increase as well.

This is quite strange because this second atom should be displaced when the PKA is getting close. I have tried to use another sample like iron and everything worked absolutely fine.

The code is:

#Problem in 3D
dimension 3

#Defining the boundary conditions
boundary p p p

#Results will be written in metal units
units metal

variable a equal 3.16
lattice bcc $a

region box block -30.0 30.0 -30.0 30.0 -30.0 30.0 side in
create_box 1 box

region nano_final sphere 0.0 0.0 0.0 40.0

create_atoms 1 box

mass 1 183.85

#pair_style eam/alloy
#pair_coeff * * W.alloy W

#pair_style tersoff
#pair_coeff * * W.tersoff W

pair_style eam/fs
pair_coeff * * W_mm.eam.fs W

neighbor 3.0 bin
neigh_modify every 1 delay 0

thermo_modify lost ignore
compute csym all ke/atom
compute eng all pe/atom
compute eatoms all reduce sum c_eng
compute strs all stress/atom NULL

dump 1 all custom 1000 minW.* id type x y z c_csym c_eng c_strs[1] c_strs[2] c_strs[3]

min_style cg
minimize 1e-15 1e-15 10000 10000

reset_timestep 0
timestep 0.0001

undump 1

velocity all create 1200.0 43458
fix 1 all nve
fix 2 all temp/rescale 100 300.0 300.0 0.5 1.0

run 1000
write_restart temp.equil
unfix 2

reset_timestep 0

fix 5 all dt/reset 10 1.0e-7 1.0e-5 0.001

thermo 10
thermo_style custom step temp pe etotal press

group PKA id 269946
velocity PKA set 0.0 50.0 -1024.4024 units box