Dear Community,

Some time ago I've mentioned a potential problem: the input files that used to work fine (vc-relax) resulted in very high stress and no convergence in cell size.

I keep getting the same (or at least related) issue in PW QE 6.7, Intel+MKL.

In PW 6.7, the exemplary stress looks like this:

       316.18        0.00        0.00    ;
          0.00       32.20       -0.78   ;
          0.00       -0.78       33.     ;

I'm not sure if my formatting persists, hence the semicolons.

There is always a row 1 column 1 (cartesian x?) component of the stress which is about an order of magnitude larger than the second largest component. Also, convergence in relax is never reached, total force remains rather constant.

This is an open-shell systems, a Lu2O3 cell with a single dopant atom at Lu site.

Every time this problem occurs - I have an electron in the system that does not want to localize at the dopant site and remains in conduction band. That might be physical or not - but it should result in some converged geometry, right?

Given the fact that this problem comes and goes - it might be related to hardware or an external library.

Where do I look for the source of it? Which external library could be corrupting data?
Or is it not an external problem?

Thank you.
Andrii Shyichuk, University of Wrocław.

Dear Community,

I've encountered a weird behaviour of several vc-relax calculations.
Namely, the SCF part is fine, but the stress part gives something like this:

total stress (Ry/bohr**3) (kbar) P= -35982.30 -0.24459504 0.00000000 0.00000000 -35981.17 0.00 0.00 0.00000000 -0.24461371 0.00002601 0.00 -35983.91 3.83 0.00000000 0.00002601 -0.24459958 0.00 3.83 -35981.83

As the steps go, total force remains about 0.25-0.3 and does not go down.

The best part: I also got that on the inputs that used to work before,
with the same version on PW.

My QE is 6.5, the release version, compiled with Intel 16 and MKL.

I am almost positive that this is a supercomputer (or even a hardware) issue:
- it came out of the the blue;
- recompilation does not help.

The question:
Did anyone ever encounter anything like that, and what that can be related to?

Thank you in advance.
Best regards.
Andrii Shyichuk, University of Wrocław.
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