Dear Madhura,
> > Thanks for the explanation. > I had always thought that DOS code also requires wavefunction files; and > that is why one needs to give the same prefix and outdir path as in scf > calculations. If code does not need wavefunctions, which files it uses > for DOS calc.s? the code needs mainly the eigenvalues, which are stored in $prefix.save/K?????/eigenval.xml files, where K????? (i.e. K00001, K00002, etc ) correspond to each kpt. > As per suggestion, I have run PDOS calc.s with the same number of pools > and processors (in case of B) and got results. That means PDOS code is > parallelized with pool implementation, but not DOS. > yes you are right, this means that pDOS is parallelized over G vectors and pools, while DOS calculation is not parallelized but is anyway compatible with the parallel environment (i.e. it does not crash if run parallel) andrea > Thanks once again, > Madhura. > > > > > Dear Madhura, > > > > the issue of using the same parallelism scheme (# of processors, # of > > pools, etc) in postprocessing calculations is mainly concerned with the > > need to read wfcs. As you wrote, if you specify wf_collect = .TRUE. you > > completely remove this issue (you can read wfcs whatever the > > parallelization > > scheme you used to produce them). > > > >>From this point of view, the main difference between DOS and pDOS > > calculations is that the former does not need to read wfcs, while the > > latter does. > > > > Moreover, the taks the DOS program has to perform is so inexpensive that > > it is performed by a single processor even if the code is run in parallel. > > This is consistent with your observation at (ii). > > > > In the case of pDOS (i.e. when running projwfc.x) if you do not collect > > wfcs you should run with the same # of processors and the same pool > > parallelism. Otherwise, as you experienced, you get a davcio error > > (some of the wfcs files were not found). > > According to me, anyway, projwfc should work with pools if the above > > conditions are fulfilled. > > > > hope it helps > > andrea > > > > > >> > >> There have been many discussions in this forum about parallelization of > >> DOS and projected DOS codes. However, some of the points were not clear > >> to > >> me, so I have performed some scf calculations for a very simple system > >> using 8 processors and with flag wf_collect 'false'. I have performed > >> same > >> calculations once without use of pools (A) and then using 2 pools (B). > >> Then using theses wavefunctions I have performed DOS and PDOS > >> calculations. Following is the summary of results and my interpretation: > >> > >> i) Pool parallelization is not implemented for both these codes. > >> > >> ii) DOS calculations: for both the cases A and B, one can calculate DOS > >> with the same no. of processors (= 8) and the results match within > >> numerical errors; even though for case B, the wavefunctions were > >> obtained > >> with pooling and DOS without it. > >> For case A, even if I use 4 processors I get identical results as when > >> I > >> use 8 processors. (Note, I have not checked with less no. of proc.s for > >> B). > >> => The condition that we need the same no. of processors and pools as > >> were > >> used in scf calculations is not necessary; and it is possible to get DOS > >> results even with wavefunctions generated with pool parallelization. > >> > >> iii) PDOS calculations: This can be calculated only in case of A and > >> using > >> the same no. of processors. If I use wavefunctions generated in case B > >> or > >> less no. of processors (= 4) with A wavefn.s then I get "davcio" error. > >> => > >> For PDOS calculations, one cannot use wavefunctions generated with pool > >> parallelization unless wf_collect flag is set to 'true' for scf calc.s; > >> also one has to use the same no. of proc.s as were used for scf calc.s > >> to > >> get projected DOS. > >> > >> Now my question is are these interpretations correct? Or they may change > >> for some other system?? Do I need to do some more checks to ascertain > >> these? If yes, what sort of tests? > >> > >> Thanks for reading this long mail patiently, but I need to clarify on > >> these points before I can start with bigger systems. > >> Sincerely, > >> Madhura. > >> > >> > >> > > > > -- > > Andrea Ferretti > > MIT, Dept Material Science & Engineering > > bldg 13-4078, 77, Massachusetts Ave, Cambridge, MA > > Tel: +1 617-452-2455; Skype: andrea_ferretti > > URL: http://quasiamore.mit.edu > > > > Please, if possible, don't send me MS Word or PowerPoint attachments > > Why? See: http://www.gnu.org/philosophy/no-word-attachments.html > > > > > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://www.democritos.it/mailman/listinfo/pw_forum > > > > > -- Andrea Ferretti MIT, Dept Material Science & Engineering bldg 13-4078, 77, Massachusetts Ave, Cambridge, MA Tel: +1 617-452-2455; Skype: andrea_ferretti URL: http://quasiamore.mit.edu Please, if possible, don't send me MS Word or PowerPoint attachments Why? See: http://www.gnu.org/philosophy/no-word-attachments.html