I perform two simulations :one is running directly and the other is using the write_restart command after 50000timesteps to conserve the state, and use read_restart to read the restart file in a new input script.The parameter settings is the same,however,after simulation,i find the atoms position is different after 65000timestep between the two simulations.I want to know this phenomenon is normal or somewhere i have done incorrectly?
On a timestep you write a restart file, LAMMPS performs
a re-neighbor, so that when you read the restart file (in a 2nd simulation)
and it performs an initial neighboring, you are more likely to
get the same answer when comparing the 2 simulations going
forward in time.
If you run a 3rd simulation (as you did) where you do not write
the restart file, then you did not perform a reneighbor on step
- That means the 3rd simulation is slightly different
than the first two, and thus the trajectories will diverge more
rapidly over time due to atoms being in a different order, etc.
15000 steps is plenty of time for two trajectories to diverge in MD.