A LDOS calculation should take more or less the same time as the calculation of the charge density, plus reading, wroting, etc.. I just tried and it took half an hour on 18 processors (CPU cores, not GPUs)
Paolo On Wed, Mar 17, 2021 at 5:26 PM Lenz Fiedler <fiedler.l...@gmail.com> wrote: > Dear Professor Giannozzi, > > Thank you so much for your answer. You are right, I did not really think > about the parallelization for the initial SCF calculation, I was more > puzzled by the pp.x calculation. If I understand you correctly, using > something like "pp.x -nk 16" might also help speed up the LDOS calculation > as well? But there also might be an upper limit of how fast this performs > and it could be that I simply have to wait a while to obtain the LDOS? As > in, except for my suboptimal parallelization strategy, the long runtime of > pp.x I observed was not due to wrong usage but simply to computational load > of the problem? > > Kind regards > Lenz Fiedler > > PhD Student (HZDR / CASUS) > > > Am Di., 16. März 2021 um 16:36 Uhr schrieb Paolo Giannozzi < > p.gianno...@gmail.com>: > >> Your supercell is small but you have a high cutoff and a large number of >> k-points, which makes the overall computational load quite heavy. Moreover >> your choice of parallelization is less than optimal: you should use both >> k-point and plane-wave parallelization, something like "mpirun -np 160 pw.x >> -nk 16" or so. For reference: I ran your Fe.pw.scf.in input in 20' on a >> small 36-core machine with two (powerful) GPU's. The nscf calculation took >> 1h20' for the calculation and is taking as much time if not more to write >> the files. Also note that not all postprocessing calculations are optimized >> for large runs. >> >> Paolo >> >> On Mon, Mar 15, 2021 at 7:23 PM Lenz Fiedler <fiedler.l...@gmail.com> >> wrote: >> >>> (resent because something went wrong with the header line) >>> >>> Hi users, >>> >>> I am experiencing a problem with pp.x. I want to calculate the LDOS for >>> a 16 Fe atom supercell using a 560 value energy grid and the 3D grid given >>> by the DFT calculation (100x100x100 grid points). I have performed the DFT >>> calculation by first doing a SCF calculation (8x8x8 k-points) and then a >>> non-SCF calculation (14x14x14 k-points) successfully. Now I am trying to >>> do: >>> >>> mpirun -np 160 pp.x -in Fe.pp.ldos.in >>> >>> but the calculation takes way longer than I anticipated. The entire DFT >>> calculation took less than a day, while for the LDOS, after about 12 hours, >>> only 20 tmp files had been written. Am I doing something wrong? Or is this >>> expected? At this rate, calculating the LDOS would take days, which is why >>> I am assuming I am doing something wrong. >>> Please find my output and input files here: >>> >>> >>> https://drive.google.com/drive/folders/1R-m5jlw1bcNxe3nBXjc4dms-IoMMp4Ir?usp=sharing >>> (the pp.out file is from a run where I investigated if a lower number of >>> CPUs helps, but that was slower, as expected.) >>> >>> Kind regards >>> Lenz >>> >>> PhD Student (HZDR / CASUS) >>> _______________________________________________ >>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu) >>> users mailing list users@lists.quantum-espresso.org >>> https://lists.quantum-espresso.org/mailman/listinfo/users >> >> >> >> -- >> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, >> Univ. Udine, via delle Scienze 206, 33100 Udine, Italy >> Phone +39-0432-558216, fax +39-0432-558222 >> >> _______________________________________________ >> Quantum ESPRESSO is supported by MaX (www.max-centre.eu) >> users mailing list users@lists.quantum-espresso.org >> https://lists.quantum-espresso.org/mailman/listinfo/users > > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users -- Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 206, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
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