No movement of atoms

LAMMPS LAMMPS Beginners
1

Dear all,

I made an input file for a standard nve simulation of argon. But when I open the dump in VMD, there is no movement of atoms, they are just still during the simulation. What might I have done wrong?

Thanks

# Monoatomic gas - Argon
# PART A - ENERGY MINIMIZATION
# 1) Initialization
units           lj
dimension       3
atom_style      atomic 
pair_style      lj/cut 2.5
boundary        p p p

#sigma = 3.405
#e/kB = 125.2

# 2) System definition
region          simulation_box block -67 67 -67 67 -67 67 
create_box      1 simulation_box
create_atoms    1 random 1000 260702 NULL 
group           all type 1

# 3) Simulation settings
mass            1 1
pair_coeff      1 1 1.0 1.0
velocity        all create 2.4 196466 dist gaussian 

# 4) Visualization
thermo 1 
thermo_style custom step atoms temp press pe ke etotal vol

# 5) Energy minimization
minimize 1e-6 1e-8 1000 10000


# PART B - MOLECULAR DYNAMICS
# 4) Visualization
thermo          1
dump            monogas all atom 10 dump.monogas.lammpstrj
atom_modify     sort 0 0.0

# 5) Run
fix             simpad all nve 
timestep        0.00001
run             5000
2

You have to look more careful. They do move, but they move very little.
You can confirm this by comparing positions in the dump file of the same atom
between timesteps.

There is nothing “wrong”, only that your timestep is about 100x smaller than it needs to be and you have a very short run (only 5000 steps at a 0.00001\tau timestep that is a total time of only 0.05\tau) with frequent trajectory output (every 10 steps). If you put this all together, there must be very little total motion when animating the trajectory in VMD.