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
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