[CP2K-user] Energy differences with identical relative coordinates

[Miguel Steiner]

Dear Cp2k developers,

just by coincidence I noticed that I get different electronic energies 
depending on the absolute coordinates of my input molecule.
I tried a simple test system with O2 in a 15x15x15x angstrom cube. I set-up 
2 different xyz files, one with 3.xx angstrom in the z coordinates and one 
with 34.xx angstrom in the z coordinate. However, both O2 molecules are 
identical in their bond length, they are simply translated to each other.
As long as I center the coordinates, I get the identical electronic energy 
of
-31.929620495691506
But if I don't center the coordinates, I get different results:
-31.929366281248029 (inside)
-31.929298672694223 (outside)

I mean, I can imagine that it leads to difficulties, if the molecule is 
placed outside of the defined cell, but especially the different energy for 
the O2 molecules that is placed within the cell, albeit not the exact 
center, confuses me.

Am I doing something wrong here or is this expected behavior? If the latter 
is the case, why aren't all coordinates centered by default (which I guess 
I will do from now on)?

Input and systems see attachment.

Thanks in advance and best regards,
Miguel
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