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

Bálint Aradi aradi at uni-bremen.de
Mon Sep 12 08:50:39 CEST 2016

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,


Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen

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