Author Topic: Unexplainable Glitch in NPT Molecular Dynamics (Possible ATK Numerical Error?)  (Read 151 times)

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Offline AsifShah

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Dear Admin,

I have been running NPT simulations (at 300K, details in attached file below) using Martyna Tobias Klien's calculator. The files are attached below.
However, I see my system suffers from a sudden glitch (shown in the pic below). I re-ran my script again but it still shows the glitch.
This has happened for other temperatures also.

Kindly state the possible reasons for this sudden change in temperature. Although grep -rni warning file.log  shows no error or warning.

(The .log file was very large, so I have grep MD in the attached file. It shows how suddenly instant temperature changes to very high values of 1000K+)

Thanks
« Last Edit: October 12, 2022, 06:59 by AsifShah »

Offline Anders Blom

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Possibly some atoms come very close to each other, if the potential is not good enough at keeping them apart.

Offline AsifShah

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But I am not using any forcefield potential. It is an ab-initio Molecular Dynamic Run.

What could possibly be wrong?

Offline Anders Blom

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Ah ok. Maybe some oddity in the Grimme term? Can the spike be correlated to some specific feature in the atom positions (if you watch the movie of the atom trajectory)?

Offline AsifShah

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I will rerun with other Grimme corrections and see if the spike repeats.