nan with fix box/relax

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1

Hi all,

I am getting Nan when using fix box/relax with the 17 Jan 2017 version. I am attaching a short input file along with the potential so you (hopefully) can reproduce the error. The potential is an EAM, and the input used to work fine with previous (before 9 Jan 2017) versions of lammps.

Thanks,
Enrique

FeCuNi.eam.GB (1.17 MB)

in.relax (798 Bytes)

out-nan (3.21 KB)

ATT00001.txt (231 Bytes)

2

Hi all,

I am getting Nan when using fix box/relax with the 17 Jan 2017 version. I am attaching a short input file along with the potential so you (hopefully) can reproduce the error. The potential is an EAM, and the input used to work fine with previous (before 9 Jan 2017) versions of lammps.

thanks for reporting. this is quite unexpected behavior and is likely
related to the recent refactoring of the neighbor list code.
in this case it looks as if adding fix box/relax results in some
inconsistency in how neighbor lists are created in binning mode.
somehow the wrong bins are used and thus atom i and atom j can be the
same atom resulting in a division by zero.

you can verify this by using nsq neighbor mode. that will run the code
very slowly, but without the NaNs due to a division by zero since r_ij
becomes zero for i==j.

i've filed this report on github as issue #347

axel.

3

Axel tells me this was fixed by some changes

we made a day ago, that will be in the next patch …

Thanks for the scripts Enrique,

Steve