Hello:
There is a problem in my simulation .I want to control a tip which has 5618 atoms move on a substrate by fix addforce 0 0 -0.01
command. the force of tip should be -56.18 in theory. when the units in lj,the force i apply to the tip output is -0.0004867525.
when i change the units to units metal or units real ,the force of tip is -56.18. is it the command units lj lead to the problem of
the tip force ? here is my in script and datafile:
3d contact simulation
units lj
boundary p p s
atom_style atomic
neighbor 0.3 bin
neigh_modify delay 5
create geometry
read_data yatou.data
lattice fcc 1
region sample block 0 30 0 30 0 30
create_atoms 2 region sample
mass 1 1
mass 2 1
mass 3 1
mass 4 1
#read_restart restart.500000
lj potentials
pair_style lj/cut 1.5
pair_coeff * * 1.0 1.0 1.12
#pair_coeff 1 4 1.0 1.0 1.12
#neigh_modify exclude type 1 1
#neigh_modify exclude type 2 2
region lower block INF INF INF INF INF 2
region newton block INF INF INF INF 10 30
group tip type 1
group sample region sample
group lower region lower
group newton region newton
group mobile subtract sample lower
group constant subtract sample lower newton
set group lower type 2
set group constant type 3
set group newton type 4
temp controllers
compute new mobile temp
velocity mobile create 0.0001 3618360 temp new
timestep 0.005
equilibrate
fix 2 constant langevin 0.0001 0.0001 0.1 3618360
fix 3 lower setforce 0 0 0
fix 6 tip addforce -0.01 0.01 -0.01
fix 4 tip rigid single
fix 1 mobile nve
fix 5 tip setforce NULL NULL NULL
dump 1 all atom 5000 dump.lammpstrj
dump_modify 1 scale no
thermo 100
thermo_style custom step pe etotal c_new f_5[1] f_5[2] f_5[3] vol
restart 500000 restart
run 2000
next is the the datafile yatou.data
5618 atoms
4 atom types
0 47.622 xlo xhi
0 47.622 ylo yhi
0 58 zlo zhi
Atoms
1 1 23.8110 21.4299 48.7420
……
……