Hi all,
I'm using velocity set command to apply constant tensile loading on 2D graphene sheet (8 nm by 8 nm). I have grouped straps on the edge of graphene sheet and pulling the straps by velocity command.
At the very high velocity (ex. velocity left set -0.1 0 0 units box), I obtained expected tensile strength and deformation process. However, at very low velocity, (ex. velocity left set -0.004 0 0 units box), the tensile loading increases but remains the same after certain value of loading, and does not proceed further until the deformation.
I tried at different temperatures (1K and 400K) but I had the same problem from both temperatures.
Could anyone help me to understand this problem and possibly have the solution?
Please find the following for my code:
# Boundary Setting
dimension 3
boundary m m p
units metal
atom_style atomic
# Graphene sheet
read_data 8by8.data
pair_style airebo 1.92 1 1
pair_coeff * * CH.airebo C
# Setup
region left block INF 11.5 INF INF INF INF units box
region right block 68.5 INF INF INF INF INF units box
group left region left
group right region right
group side_graphene union left right
group main_graphene subtract all side_graphene
group sheet union side_graphene main_graphene
set group left type 1
set group right type 1
velocity all create 1.0 123456 dist gaussian # Temperature = 1.0 K
velocity all zero linear
velocity all zero angular
thermo 500
thermo_style custom step temp atoms lx ly lz pxx pyy pzz
thermo_modify lost warn norm yes flush yes
timestep 0.001
dump 1 all cfg 1000 initial.*.cfg id type xs ys zs
#Energy equilibration
fix 1 all nve
fix 2 all temp/rescale 10 1.0 1.0 10 0.5
run 10000
unfix 1
unfix 2
undump 1
reset_timestep 0
#Tensile Loading
fix 1 all nvt temp 1.0 1.0 10.0 drag 1
velocity left set -0.1 0 0 units box
velocity right set 0.1 0 0 units box
fix 2 side_graphene setforce 0.0 0.0 0.0
thermo_style custom step temp atoms lx ly lz pxx pyy pzz
thermo_modify lost warn norm yes flush yes
dump 3 all cfg 1000 deform.*.cfg id type xs ys zs
run 100000000
Regards,
Dong Kim