[Pw_forum] phonon calculation for large system

Gabriele Sclauzero sclauzer at sissa.it
Thu Apr 30 09:46:41 CEST 2009

zq wu wrote:
> Dear pwscf users,
> I need to do phonon calculation for large system (several hundreds atoms 
> per cell). Since i can use lots of processors, I plan to submit many 
> jobs,  each of which will calculate 1 phonon mode. But i do not know 
> whether it is available to get final dynamic matrix from these separate 
> runs and how to do it. Can any one help me?     
>  Currently, phonon modes are calculated one by one in sequence in phonon 
> calculation. Can we do some parallelization here? Can we divide the 
> processors into several groups and let each group take care of one or 
> more modes in a way similar to K-points parallelization?  I think that 
> the parallel efficeincy for modes parallelization should also be close 
> to K-points parallelization since the phonon modes calculation is 
> independent of each other.  The modes parallelization should be very 
> useful for system with large numbers of atoms.  Does anyone have the 
> idea how hard it is to do the modes parallelization?  

If I correctly understood, i think that this kind of parallelization has already been 
exploited in the latest versions of CVS, in order to use ph.x on the GRID. I don't know if 
all the related problems have been fixed at this stage (have they, Paolo?), but you can 
try to download the CVS and use the keywords start_q, last_q, start_irr, last_irr (see 
INPUT_PH) to split your job in many independent jobs. Sorry, I don't know the details, but 
at least now you're aware that there is this possibility available (though not extensively 
tested, I think, so use _with_ _care_ and help debugging, please).



> Thanks
> Zhongqing
> CACS  University of Southern California
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| Gabriele Sclauzero, PhD Student                  |
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