order of particles in the dumpfile

Dear Lammps users

My question may look basic but I want to check whether my simulations are right or not.

I used dump command to give me the unwrapped positions of the particles, but as I was post-processing the dump files with my codes, I saw that the order of particles within the dump files are not the same from one file to the other in a single simulation. I wanted to know how this order is defined? Are the particles sorted considering their positions in the simulation box?

Best Regards

In general, the ordering is not guaranteed from one frame to the next. They're written out in the order that each processor has them in memory. You can force atoms to be sorted using the sort option of the dump_modify command.