Atom indexes changed

Hi, all

The developer guide mentioned “particle indexes are usually changed every timestep because of sorting”. So when I use command “dump 5 all custom 400000 dump.atom id type mol x y z”, am I supposed to expect the atom id info dumped from each dump file is changed, and atom with id 1 in one timestep is not necessarily the same atom with id 1 in the next timestep?

If so, I do need the index of the atom to be the same for each timestep, to track the motion of each atom and check topology violation. Is there any way to do it?



Hi Tao,

The fragment you cited is not about atom ids, but indexes in internal LAMMPS arrays. You don’t have to worry about it as long as you don’t modify the source code. Atom id is constant for a given atom (except for some special cases, e.g. deleting atoms with “compress yes”).