Dear all,
I am trying to deposit Ge atoms on a 2x1 Si (100) sample with the Tersoff potential. I’ve done the same experiment with the potential of Stillinger Webber without any problems. The only difference is the temperature used, because as Tersoff’s potential overestimates the melting temperature of Si and Ge. In the case of Tersoff I used temperatures between 1200 and 2200 K. The deposition rate is 1 atom every 2500 steps. The time step is 1 fs. The sample was previously created with 12 Si layers. The first 4 layers are fixed, the next 4 are rescaled to the stipulated temperature every 500 steps and the last 4 are free.
The code is:
# ------------------------ INITIALIZATION ----------------------------
processors 12 7 1
units metal
boundary p p f
atom_style atomic
newton on
# ----------------------- ATOM DEFINITION ----------------------------
read_data data_dep_term
mass 1 28.085e95
mass 2 28.085
mass 3 28.085
mass 4 72.64
group fixed type 1
group substrater type 2
group substrate type 3
group addatoms type 4
region myblock block 0.0 92.7576 0.0 92.7576 100.00 100.00
# ------------------------ FORCE FIELDS ------------------------------
# Potencial Tersoff
pair_style tersoff
pair_coeff * * SiGe.tersoff Si Si Si Ge
neighbor 0.0 bin
neigh_modify every 1 delay 0 check no
timestep 0.001
run_style verlet
# ----------------------------------------------------------------------------------
fix 1 all nve
fix 2 fixed setforce 0.0 0.0 0.0
compute temp0 fixed temp
compute temp1 substrater temp
compute temp2 substrate temp
compute vol all voronoi/atom
compute stressat all stress/atom NULL
fix depGe addatoms deposit 13824 4 2500 65445 region myblock vz -7.0 -7.0 units box
compute temp3 addatoms temp
compute_modify temp3 dynamic/dof yes
#------------ Equilibration
fix equilib substrater temp/rescale 500 1464 1464 1.0 1.0
variable paso equal step
#----Informacion en lammps.out ------------#
thermo_style custom step atoms temp c_temp0 c_temp1 c_temp2 c_temp3 ke epair etotal press
thermo_modify flush yes
thermo 100
#To obtain Potential energy per atom
compute poteng all pe/atom
dump AtomPosVel all custom 500 sitf.* id type x y z vx vy vz
dump AtomPosVel1 all custom 50000 pos.* id type x y z c_stressat[1] c_stressat[2] c_stressat[3] c_stressat[4] c_stressat[5] c_stressat[6] c_vol[1]
restart 50000 restart1 restart2
run 35000000
I’ve used the August 2019 version.
The problem is:
Several Ge atoms undergo scatering once they reach the surface with Tersoff’s potential. What can I do to fix this? Is it unavoidable? Are there certain things that need to be taken into account?
I have tried for different incident energies of Ge particles, the scattering of Ge atoms persists.
I have a short video of the Ge scattering. I can send you the video if you request me it an email at luis.martin.encinar@…9301…
Thanks.
Best regards.
in.si.txt (1.99 KB)