[DFTB-Plus-User] On parallel version of DFTB+

[Ben Hourahine]

Hello Huang,

just to add to Bálint's comments, setting

WriteHSDInput = No

will prevent the code from trying to write the dftb_pin.hsd file which
is where MAXRECL causes problems.

As Bálint mentions, errors usually indicate atoms too close together,
but the pdpotrf routine in some versions of ScaLAPACK can be a little
temperamental. If you cannot find an obvious problem with the atom
coordinates, is there an alternative version of the library installed
that you can try?

Regards

Ben

On 12/09/16 07:50, Bálint Aradi wrote:
> Dear ZhaoHui Huang,
> 
>> I have an issue from running parallel DFTB+. My unit cell contains
>> 26,000 atoms and I just want to relax the structures a few steps. By
>> running the code, I first get output overflow error message, then I
>> increase MAXRECL parameter defined in HSDParser package. It runs
>> indeed. but It failed by SCALAPACK error,
> 
> Yes, correct, this MAXRECL just comes from the fact, that we write out
> the coordinates with one write statement, which at those system sizes
> can be unfortunately problematic (depending on the compiler).
> 
>> MAXNEIGHBORS: 8847 iSCC Total electronic   Diff electronic      SCC
>> error Operation failed! ppotrf in scalafx_ppotrf_dreal Info: 23233
>>
>>
>> Is there any code developer who is familiar with this part of code?
>> thanks.
> 
> ppotrf is the wrapper around the pdpotrf routine in ScaLAPACK, which
> does the Cholesky-decomposition. When it fails, it is often an
> indication, that your overlap matrix is ill defined. Maybe some atoms
> are unphysically close to each other (eventually due to periodic
> boundary conditions)?. Can you somehow check, how close the atoms are to
> each other. You may do it by analyzing the first few elements of the
> iNeighbors(0:,1:nAtom) array. The first index goes over the neighbors of
> a given atom (second index). It is never printed out anywhere, but it
> should tell you when something is fishy.
> 
>   Best regards,
> 
>   Bálint
> 
> 
> 
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      Dr. B. Hourahine, SUPA, Department of Physics,
    University of Strathclyde, John Anderson Building,
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