[ase-users] Instability in NPT module when comparing ASE 3.17 to ASE 3.18

[Jakob Schiøtz]

Dear Andrew,

There are no recent changes in the NPT module a part from some changes to the docstrings.  There could be changes to the LAMMPS interface, I do not know anything about that part of the code.

In general NPT dynamics is not terribly stable.  It works great at maintaining constant temperature and pressure, but is not good at equilibrating toward the correct temperature, as it tend to set up an oscillation.  However, judging from your log file that is not the case, it looks like the system has the right temperature and then suddenly blows up.  I unfortunately do not know what could be causing this, except that I suspect it may be related to the lammps interface somehow.

Best regards

Jakob
--
Jakob Schiøtz, professor, Ph.D.
Department of Physics
Technical University of Denmark
DK-2800 Kongens Lyngby, Denmark
http://www.fysik.dtu.dk/~schiotz/



> On 12 Nov 2019, at 09.33, Andrew Logsdail via ase-users <ase-users at listserv.fysik.dtu.dk> wrote:
> 
> Dear all,
> 
> I am observing an instability with ASE v3.18 when using the NPT module with LAMMPS. Attached are a python script and outputs for ASE v3.17 (working) and v3.18 (not-working) - here LAMMPS has just been installed using the standard package manager (dnf) on a desktop machine.
> 
> Has anyone any comments or insight into what is causing these problems? I can't tell if it is a bug or change in the NPT modules behaviour.
> 
> Many thanks in advance,
> 
> Andy
> 
> --
> 
> Dr. Andrew Logsdail
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> <mdFe.log.ase.3.18.1><mdFe.log.ase.3.18><mdFe.log.ase.3.17><Jelinek_2012_meamf><Jelinek_2012_meam.alsimgcufe><NPTFe.py.txt>_______________________________________________
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