[lammps-users] disordered data file

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1

Hi,

I have been running a two-step granular simulation with 2 separate input files. The first simulation I run with mpi and when using write_data, I get a data file that is disordered. That is, the atom ids are not in ascending order. I then call that data to my second simulation which I run in serial (have tried mpi too but to no avail) but it gives me a segmentation fault.

After a lot of trial and error debugging, I noticed that if my data file for the second simulation is in ascending order, it does seem to work. This is because I had done simulations where the first simulation is also run in serial which results in an ordered data file.

I don’t know what is going on here. Can anyone care to explain or provide an easy workaround without me having to write a script to correct the data file? I don’t see any mention of the data file being required to be written in ascending order in the docs.

Best,
Devanjith

2

The entries in data files can be in any order.

If the order makes a difference then that is either an indication of a more general problem in your simulation setup (that just doesn’t show up in the first case by chance) or a bug in the LAMMPS code.

Can you provide us with a (very) small input deck that can reproduce this behavior?

Please also test with the latest LAMMPS version. If this is a bug in the LAMMPS code, it may already have been fixed.

Axel.