[lammps-users] Unexpected Large displacement of atoms during equilibration

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1

Hi,
I am using LAMMPS for doing Cascade simulation. I am experiencing a strange error. During equlibration process at 100 K, I have seen that almost all the atoms are moving larger than the specified cut-off distance (0.3* lattice constant). From 21000 steps a few atoms moved by the specified distance and at ~30000 steps , almost all the atoms have moved. Note that, i have not introduced any high energetic particle at this stage.

The result is unreasonable. Can anybody plz mention where I am making the mistake? I am posting part of my INPUT file of relevance below.

2

Have you visualized the system and watched the atoms move?
Presumably they are doing something physical, else you will
see it.

Steve

3

Hi Steve,

4

It seems like your momentum is not conserved. Think about it. why it is happening?

5

Hi,
At last I solved the problem. I made a silly mistake. In my simulation the system temperature is 100 K. But i did not initialize the atoms velocities and then rescaled the velocities to maintain the system temperature at 100 K. After incorporating the specific command “velocity…” , the simulation is giving expected results and without any shifting of the simulation box during equilibration phase.

Thanks for the help.
Regards.
Prithwish

Vikas Varshney wrote: