The ABINIT Users Mailing List ( CLOSED )

[Latévi Max LAWSON DAKU <Max.Lawson@unige.ch>]

On 21. 11. 09 22:51, Yann Pouillon wrote:
> Hi,

Hi, Yann,

I thank you a lot for your answer.

> Latévi Max LAWSON DAKU <Max.Lawson@unige.ch> ha escrito:
>
> > I would like to use the band/FFT/k-point parallelisation, and several
> > distributions have been proposed for the number of processors.
> > The distributions retained read (npkpt, npband, npfft)=(2, 150, x),
> > with x a positive integer.
> >
> > But the calculations tend to be extremely slow even when using
> > 3000 cpus. In this last case, the code actually segfaults after having
> > output:
> >
> >    ITER STEP NUMBER     1
> >     vtorho : nnsclo_now=  2, note that nnsclo,dbl_nnsclo,istep=  0 0  1
> >      ****  In vtorho for isppol= 1
> >     starting lobpcg, with nblockbd,mpi_enreg%nproc_band 1 150
> >     condition number of the Gram matrix= 59476636.484308563
> >     Lobpcgccwf: restart performed
>
> I have the same problem with nanotubes using PAW on a different 
> architecture. The segfault disappears when I reduce the cell size 
> (which in absolute I don't want). I've been trying to change the 
> following parameters:
>
>   * increasing nband
>   * varying npband, npfft, bandpp
>   * increasing diecut, dielam
>   * varying iprcel, iprcch
>   * increasing nnsclo
>   * trying both metallic and non-metallic nanotubes

Unfortunately, I cannot reduce the cell size. But I will also play with 
these
parameters.

All the best,
Max


> I also very carefully checked the positions of the atoms. But the 
> electronic ground-state SCF never converges.
>
> I'm pretty sure there is a memory leak somewhere, but I was unable to 
> locate it. Smells to me like a problem in the preconditioning, but may 
> be elsewhere.
>
> If somebody has more insight about this, I would greatly appreciate 
> any hint.
>
> Best regards,
>
> Yann.

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Latevi Max LAWSON DAKU
Universite de Geneve - Sciences II
30, quai Ernest-Ansermet  
CH-1211 Geneve 4 
Switzerland 

Tel: (41) 22/379 6548 ++ Fax: (41) 22/379 6103
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