fix ave/chunk affects the dynamics?

Dear all,

Please find enclosed 2 input scripts, in.ok and in.fail, and the
corresponding log files. One is working fine, and the other is
producing lost atoms. The only difference between these input scripts
is that at some point I added a fix ave/chunk:

$ diff in.ok in.fail
64,65c64,65
< #compute bin7 all chunk/atom bin/1d z 0.0 0.05 units box
< #fix 7 liquid ave/chunk 10 100 1000 bin7 density/number temp vx ave
running overwrite file chunk_liquid.time

fix_ave_chunk.tgz (5.27 KB)

This looks like a bug - I’m working on it …

Steve

Dear Steve,

Thank you very much. It looks like the fix setforce / fix aveforce are
becoming ineffective somehow when the fix ave/chunk is defined, and
when I cut the last run into two successive run 1000, but I cannot
tell you much more...

Best regards,
Laurent

Hi Laurent - I posted a PR that should fix this problem. It was a bug having
to do with compute chunk/atom deleting an internal fix it creates, when
the caller (your fix ave/chunk) was deleted. The setup for the run following
those deletes, was getting confused about which fixes to invoke in the subsequent

run, leading to bad dynamics.

So it will be in the next patch release. Or you can look at the changes,
all in Modify::init().

Thanks for the example scripts that triggered the problem, Very helpful.

Steve

Dear Steve,

Thank you very much for fixing this problem!

Best regards,
Laurent