Not Changing energy in output

LAMMPS LAMMPS Beginners
1

Dear Lammps users,

Thanks for taking your time to look at my basic question in advance…

First of all, I am using LAMMPS that was released on 29Aug2024. I also built lammps to use Deep-MD kit, so that I can use my trained deepmd potential. My system is a simulation box that is full of liquid water. I am trying to run a langevin thermostat with the following input file below:

units real
boundary p p p
atom_style atomic

neigh_modify delay 5 every 5 check yes

pair_style deepmd comp_slab_water.pb
read_data waterbox.data
pair_coeff * *

thermo 100
thermo_style custom step temp etotal pe ke vol press lx ly lz
thermo_modify flush yes

timestep 0.5

velocity all create 300.0 4928459

fix 1 all langevin 300 300 50 48279
dump 1 all custom 500 water.strj id type x y z

run 100000
write_data water_nvt.data

For some reason, my temperature, total energy, pes, kinetic energy are all staying constant during a whole simulation, and I think this is not normal (I thought there should be some fluctuation of these until it reaches equlibration).

Can you please let me know whether there’s something I don’t understand, or if I am missing information in lammps documentation?

I appreciate for your help again.

Best,
Dunyi

2

Please have a look at your log file and search for warnings. There should be one that explains what happens.

3

Thanks, Dr. Kohlmeyer

I figured out the reason – I had to add fix that include time integration and I missed it in documentation as well. I apologize and thanks for your guidance!

Dunyi