[Pw_forum] Parallel bandstructure calculations

Nicki Frank Hinsche nicvok at freenet.de
Mon Aug 23 16:32:13 CEST 2010

Hi there,

I am currently doing calculations of iso-energy surfaces on doped  
semiconductors. Therefore I generate with an external program a quite  
big k-point mesh for which I want to determine the eigenvalues and  
later on construct the iso-energy surface with a tetrahedron method.  
My problem is the running time of the bandstructure calculation.

The size of the unit (super)-cells is in the order of 30-50 atoms,  
containing 1 or 2 different atomic species. For k-points in the order  
of 4000-6000 the eigenvalues have to be calculated (most often around  
50-100 ev's for each k-point).

After the scf-calculation is done quite fast, I am running the nscf  
bandstructure calc. with the command

mpirun -np 32 pw.x -npool 4 -diag 16

but the calculation isn't done parallel, as the output says:

      Parallel version (MPI), running on    32 processors
      K-points division:     npool     =    4
      R & G space division:  proc/pool =    8

      Subspace diagonalization in iterative solution of the eigenvalue  
      a serial algorithm will be used

due to this, the calculation runs much longer than 72 hours...to long  
for me and our cluster system

So is there a possibility to parallelize the bandstructure calculation  
efficiently and to reduce tje calculation time?

thanks in advance,


Nicki Frank Hinsche, Dipl. Phys.
Institute of physics - Theoretical physics,
Martin-Luther-University Halle-Wittenberg,
Von-Seckendorff-Platz 1, Room 1.07
D-06120 Halle/Saale, Germany
Tel.: ++49 345 5525462
Fellow of the International Max Planck Re-
search School-MPI for Microstructure Physics

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