[Wien] SegFault in lapw2 when using the -fc switch

[Peter Blaha]

Hi,

Sorry, but here it is hard to help. I tried your case quickly and it runs without problems.
It has only one force on the second atom in z-direction and even this force is very small
(2-3 mRy/bohr, so min stopped after 2 steps.

One thing I noticed is that your positions are not well described:

ATOM  -2: X=0.33333334 Y=0.66666670 Z=0.25000000
           MULT= 2          ISPLIT= 4
       -2: X=0.66666666 Y=0.33333330 Z=0.75000000

should be changed to

ATOM  -2: X=0.33333333 Y=0.66666667 Z=0.25000000
           MULT= 2          ISPLIT= 4
       -2: X=0.66666667 Y=0.33333333 Z=0.75000000

I recommend that you restart in a fresh directory with corrected positions.
After   init_lapw -b
use:    run_lapw -fc 1

This should run a normal scf cycle, but at the last iteration it will change case.in2
and replace TOT by FOR, triggering additional force computation in lapw2 (which seem to
crash in your case).

If it crashes again, maybe you can send some more info about the crash.
(do   x lapw2     by "hand")

A possibility for debugging is:
cd $WIENROOT/SRC_lapw2
edit Makefile and put -C -traceback  in  FOPT
make
cp lapw2 ..

then run    x lapw2     again and see if there are any useful informations.

---------
Another trial:   make the RMT of both atoms smaller by 0.2 bohr (2.3 and 2.05) and try again from the beginning.

and: does the same problem happen with any force calculation ? Can you try the TiO2 (rutile) example from
the UG ?

PS: the only "file corruption" can occur in case.in1, where EF is eventually set to a nonsense value
Reset it to the values from the start.

PPS: I also heard the first time the comment from Stefan Cottenier, that he had sometimes similar
problems.

Am 16.05.2012 09:22, schrieb vivien badaut:
> Dear WIEN2k users
>
> I am using WIEN2k since a few month, and I am studying the compound IrTe2 on a local cluster (Centos, with compilator with ifort 11.1) since a few weeks without any significant
> problem.
> I converged successfully the system to -ec 0.00000001 and -cc 0.0001 without any problem.
> However, I recently tried to minimize the positions of the atoms in the cell.
> During the procedure, after a few iterations, I get a SegFault in lapw2. I was able to trace it back to the use of the -fc switch un run_lapw, which causes this error -
> independently of the value set for the forces convergence criteria.
> Additionally, when I get this SegFault, the files are then corrupted and I am unable to relaunch the calculation even after suppressing:
> *broyd* and *vector. I am now very stuck and I might say a bit frustrated, as I have no idea of where to look to solve it.
>
> Any ideas of parameters/values to tests or modules to check are welcome.
>
> I attached the *struct, and you can use the default setting for generating in1 and in2.`
>
> Regards,
>
> Vivien Badaut
> Computational Condensed Matter Physics Laboratory,
> RIKEN, ASI, Japan
>
>
>
>
>
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien

-- 

                                       P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
--------------------------------------------------------------------------