Dear Lammps users,
I want to simulate graphane island on the graphene substrate.
I need to fix zero the linear(along x,y) and angular momentum of the island. But despite using:
velocity … set 0 0 0
fix … … momentum 1 linear 1 1 0 angular
I still get small rotation along the z-axis which I can not understand why.
Here:
######## Initial
boundary p p f
atom_style full
units metal
######## data
read_data graphene_120*120_rot_0.data extra/atom/types 3
read_data circlar-graphAne-r-35-tilt-90.data add append offset 1 0 0 0 0 shift 58.14 66.7 0
group layer_down type 1
group layer_up type 2 3 4
group layer_up_C type 2
group layer_up_H type 3 4
displace_atoms layer_up rotate 58.14 66.7 0 0 0 1 2.8
velocity all set 0.0 0.0 0.0
####### pairs
pair_style hybrid airebo 2.5 airebo 2.5 lj/cut 6.5 lj/cut 9.0
pair_coeff * * airebo 1 CH.airebo NULL C H H
pair_coeff * * airebo 2 CH.airebo C NULL NULL NULL
pair_coeff 1 2 lj/cut 1 0.00284 3.40 6.5
pair_coeff 1 3 lj/cut 2 0.00150 2.65 9.0
pair_coeff 1 4 none
dump 1 all atom 10000 dump_.lammpstrj
######## computes
compute peatomH layer_up_H pe/atom
compute AvePotEngAtomH layer_up_H reduce ave c_peatomH
compute peatomC layer_up_C pe/atom
compute AvePotEngAtomC layer_up_C reduce ave c_peatomC
compute peatomUP layer_up pe/atom
compute AvePotEngUP layer_up reduce ave c_peatomUP
compute TempLayerUp layer_up temp
######## Pre-run sets
timestep 0.001
thermo_style custom step temp c_TempLayerUp pe ke c_AvePotEngAtomC c_AvePotEngAtomH c_AvePotEngUP
thermo_modify norm no
thermo 100
fix LANGEVIN layer_up langevin 1.0 50.0 0.1 178796
fix NVE layer_up nve
fix MOM_up layer_up momentum 1 linear 1 1 0 angular
fix freeze_down layer_down setforce 0.0 0.0 0.0
######## run 1
run 100000
write_data system_*.data
######## run 2
unfix LANGEVIN
fix LANGEVIN layer_up langevin 50.0 0.0 0.1 178796
run 500000
write_data system_*.data
######## run 3
unfix LANGEVIN
run 80000
write_data system_*.data
Best regards,
Ali Khosravi