[Pw_forum] Pw_forum Digest, Vol 15, Issue 11

[clie]

dear, L.F.Huang, you will be waiting for several weeks or one month until the
calculation finished, i guess. 
> Message: 7
> Date: Fri, 5 Sep 2008 10:33:27 -0400 (EDT)
> From: Axel Kohlmeyer <akohlmey at cmm.chem.upenn.edu>
> Subject: Re: [Pw_forum] time for calculation of el-ph interactions of
> 	graphene supercell
> To: "L.F.Huang" <lfhuang at theory.issp.ac.cn>
> Cc: pw_forum at pwscf.org
> Message-ID: <Pine.LNX.4.64.0809051023550.26272 at localhost.localdomain>
> Content-Type: text/plain; charset="gb2312"
> 
> On Fri, 5 Sep 2008, L.F.Huang wrote:
> 
> LFH> Dear PWSCF developers and users:
> LFH>   I am calculating a graphene supercell with one H atom one it, and I
> LFH> take 4*4*1 size of supercell now, and there are 33 atoms with 32 C atoms
> LFH> and 1 H atom. I calculate its phonon dispersions with 13 nodes with 2G
> LFH> random memory for each node. When frequencies of one phonon mode are
> 
> dear l.f. huang,
> 
> more important that the amount of memory in your nodes would 
> be know what kind of interconnect (gigabit, infiniband, myrinet, ...)
> you have and how you run in parallel (g-space parallelization only, 
> g-space+k-points, ...) and what type and how many cpus/cores per node 
> you have and even what kind of parallel library and math library you use.
> all of that can have a serious impact on performance.
> 
> have you done a scaling test for the first part of the calculation?
> unless you are smart about it, adding more nodes does not necessarily
> speed up your calculations, specifically, if you have only a gigabit
> ethernet interconnect.
> 
> please see, e.g., 
> http://www.democritos.it/pipermail/pw_forum/2008-June/009293.html
> for a demonstration of how one can affect performance through the
> way the QE codes are run.
> 
> LFH> calculated, the program enter into calculation of electron-phonon
> LFH> interactions. But it has passed nearly 30 hours, and the calculation of
> LFH> el-ph interaction still not completed! And for graphene unit cell with
> LFH> 2 C atoms, this process just costs about 10 seconds.
> 
> you should be aware of the fact, that this kind of calculation does not
> scale linearly; the cost of an scf caclculation alone generally goes
> up by about an order magnitude when doubling the system size.
> 
> cheers,
>    axel.
> 
> LFH>   I don't know it is normal that the calculation of el-ph interaction
> LFH> of my graphene supercell costs so much or so much more time? Any one
> LFH> has the experiences in the el-ph calculation of supercells? Could anyone
> LFH> tell me how can I do or how much time I would expect to wait?
> LFH> 
> LFH> Thanks very much!
> LFH> Best Wishes!
> LFH> 
> LFH> Yours Sincerely
> LFH> L.F.Huang
> LFH> 
> LFH> ======================================================================
> LFH> L.F.Huang(???) lfhuang at theory.issp.ac.cn
> LFH> ======================================================================
> LFH>  Add: Research Laboratory for Computational Materials Sciences,
> LFH>       Instutue of Solid State Physics,the Chinese Academy of Sciences,
> LFH>       P.O.Box 1129, Hefei 230031, P.R.China
> LFH>  Tel: 86-551-5591464-328(office)
> LFH>  Fax: 86-551-5591434
> LFH>  Web: http://theory.issp.ac.cn (website of our theory group)
> LFH>       http://www.issp.ac.cn    (website of our institute)
> LFH> ======================================================================
> LFH> 
> LFH> 
> LFH> _______________________________________________
> LFH> Pw_forum mailing list
> LFH> Pw_forum at pwscf.org
> LFH> http://www.democritos.it/mailman/listinfo/pw_forum
> LFH> 
> 
> -- 
> =======================================================================
> Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
>    Center for Molecular Modeling   --   University of Pennsylvania
> Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
> tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
> =======================================================================
> If you make something idiot-proof, the universe creates a better idiot.
> 
> ------------------------------
> 
> Message: 8
> Date: Fri, 05 Sep 2008 16:44:09 +0200
> From: Paolo Giannozzi <giannozz at democritos.it>
> Subject: Re: [Pw_forum] time for calculation of el-ph interactions of
> 	graphene supercell
> To: PWSCF Forum <pw_forum at pwscf.org>
> Message-ID: <48C145B9.9080705 at democritos.it>
> Content-Type: text/plain; charset=GB2312
> 
> L.F.Huang wrote:
> 
>> Could anyone tell me how can I do or how much time I would expect to wait?
> 
> nobody can tell you anything like this. You should try to have an
> idea of the needed time by trying first with the smaller cell, then
> with a small  supercell, etc..
> 
> Paolo
> -- 
> Paolo Giannozzi, Democritos and University of Udine, Italy
> 
> 
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> End of Pw_forum Digest, Vol 15, Issue 11
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