Hello.
I am simulating a system where I have deposited H atoms on Si surface. I am trying to see the effect of temperature and electric field on H atoms and dumped Kinectic Energy of H. When there’s no Electric field in the system, H shows random hopping and KE of H shows random values due to Temperature (I have Vx, Vy, and Vz values). Again, when I am applying Efield, I observed H hopped on Si atoms making bonds (bonds observed from bond record files and OVITO) in the direction of Efield. However, the KE of H fall down to nearly zero and increased over time, which represents the characteristics of free particles (I have only Vx values, Vy, Vz are zero).
-
If H is making bonds while hopping, why it’s KE and Velocity is always increasing? Why Vy, Vz becomes 0? Why is there no effect of temperature?
-
As per my understanding, the KE or Velocity should fall at the time of bonding. Is there any explanation from LAMMPS perspective?
-
When Efield is applied, it seems there is no effect of temperature. Any possible way to see both the effects of temp and Efield?
Following is the code:
units real
dimension 3
boundary f f f
atom_style full
lattice diamond 5.4307
region box block 0 13 0 7 0 7
create_box 2 box
region silicon block 0 13 0 7 0 2
group silicon region silicon
create_atoms 1 region silicon
group hydrogen type 2
pair_style reax/c NULL
pair_coeff * * ffield.txt Si H
mass 1 28.0855 # Si
mass 2 1.008 # H
neighbor 2.0 bin
neigh_modify every 1 delay 0 check no
timestep 0.05
fix 1 all nve
fix 2 all langevin 380 380 2 587283
region slab block 0 13 0 7 6 7
group slab region slab
fix 5 hydrogen deposit 1 2 100 17895 region slab vz -2.2 -2.2
fix 6 hydrogen deposit 1 2 100 14938 region slab vz -2.2 -2.2
fix 7 hydrogen deposit 1 2 100 83659 region slab vz -2.2 -2.2
fix 8 hydrogen deposit 1 2 100 54320 region slab vz -2.2 -2.2
fix 9 hydrogen deposit 1 2 100 19283 region slab vz -2.4 -2.4
fix 10 hydrogen deposit 1 2 100 30045 region slab vz -2.2 -2.2
fix 11 hydrogen deposit 1 2 100 23190 region slab vz -2.1 -2.1
compute eng all pe/atom
compute eatoms all reduce sum c_eng
compute reax all pair reax/c
variable eb equal c_reax[1]
fix parameter all qeq/reax 1 0.0 12.0 1e-6 param.qeq16
thermo_style custom step atoms temp c_eatoms v_eb
thermo 100
thermo_modify lost warn
fix forty all reax/c/bonds 100 x_bondrec.txt #pg 1066
fix fifty all reax/c/species 1 2 100 deposition.out element Si H cutoff 1 2 0.3
compute ke_all all ke/atom
dump 2 all custom 20 velocity.lammpstrj id type q x y z vx vy vz c_ke_all c_eng
min_style cg
minimize 1e-25 1e-25 5000 10000
run 500
###If i don’t use these commands of velocity and setforce, Efiled seems not working
velocity silicon set 0 0 0
velocity hydrogen set 0 0 0
fix 15 silicon setforce 0.0 0.0 0.0
fix 16 hydrogen setforce 0.0 0.0 0.0
#---------Electri Field-‘X’-----------------------------
fix electric all efield 0.00003 0.0 0.0
run 1400000
variable natoms equal “count(all)”
variable teng equal “c_eatoms”
variable length equal “lx”
variable ecoh equal “v_teng/v_natoms”