Hi everyone.
I am trying to simulate the indentation of a silicon substrate using a diamond. The atoms in the mobile zone are seen to explode and move randomly in the direction of the free surface. When I set the velocity of this group to 0, I get the desired result but I know this is bad dynamics. My question is: how do I keep the atoms of a group in place even after assigning a non_zero velocity and fix nve.
The following is a part of my input file.
######## INITIALIZATION
units metal
dimension 3
boundary p p p
atom_style atomic
variable latparam equal 5.43
######## SIMULATION BOX
region simulationbox block 0 76.02 0 150 0 59.73 units box
create_box 2 simulationbox
mass 1 12.01
mass 2 28.0855
######## SUBSTRATE
lattice fcc ${latparam}
region Si block 0 76.02 0 76.02 0 59.73 units box
create_atoms 2 region Si units box
group substrate region Si
######## ZONING OF SUBSTRATE
region mobile block 0 76.02 10.86 76.02 0 59.73 units box
group mobile region mobile
region thermobile block 0 76.02 5.43 76.02 0 59.73 units box
group thermobile region thermobile
group thermo subtract thermobile mobile
group fixed subtract substrate thermobile
fix 1 fixed rigid single
######## INDENTER
lattice fcc 3.57
region diamond sphere 30 90 40 8 units box
create_atoms 1 region diamond units box
group indenter region diamond
fix 3 indenter indent 10 sphere 30 90 40 8 side out units box
neighbor 2.0 bin
neigh_modify delay 0 every 1 check yes
######## INTERATOMIC POTENTIAL
pair_style hybrid morse 9 tersoff tersoff
pair_coeff * * tersoff 1 SiC.tersoff C NULL
pair_coeff * * tersoff 2 Si.tersoff NULL Si
pair_coeff 1 2 morse 0.435 4.6875 1.9475 1.5
velocity mobile create 273 4186532 dist gaussian mom yes rot yes
velocity thermo create 273 4186532 dist gaussian mom yes rot yes
fix 19 thermo temp/rescale 1 273 273 0.5 1.0
fix 70 mobile nve
######## ENERGY MINIMIZATION
minimize 1.0e-15 1.0e-15 1000 10000
min_style cg
dump minimize all xyz 100 dump.minimize
run_style verlet
thermo_style custom step temp ke pe
thermo 500
reset_timestep 0
run 12000
Any advice will be appreciated. Thanks
Chionye
Aerospace and Mechanical Engineering, SLU