On 05/08/2015 18:50, Andrea Dal Corso wrote: > On Wed, 2015-08-05 at 17:18 +0200, Merlin Meheut wrote: >> Dear PWSCF users, >> >> I recently discovered with great interest the possibilities to >> parallelize phonon calculations using the -nimage option of ph.x. >> (example given in espresso-4.3.2/examples/GRID_examples). >> > GRID examples refer to grid splitting, meaning that you split the > calculation using start_irr, last_irr etc. and in principle the > calculation can run in different machines. Then you have to collect the > files yourself to finally obtain the results.
Sorry I mixed up both. Actually, I used -nimage (as explained in Doc/INPUT_PH.txt of version 4.3.2), but I would like to restart with grid splitting. Thank you for the reference to the example. >> However, I had a problem when performing calculations at gamma-point: >> for other q-points (therefore with epsil=.false. and zue=.false.) >> everything went as planned, but with q=0 (and epsil=.true. and >> zue=.true.), this just did not work. I took 80 processors divided into 4 >> images, and instead of dividing the different representations into 4 >> pools, the four groups of processors realized the same calculation, >> computing the same representations. I killed the calculation at some >> point (I have computed the electric fields, effective charges and 218 >> representations out of 564). I would like now to finish the computation >> without redoing it, and I have several questions to achieve this goal: >> > Are you sure that all the images made the same phonon calculations, or > all images made the electric field calculation but the phonon modes were > different? The names of the partial dynamical matrices (dynmat.1.$irr.xml) are the same, the files (e.g. _ph0/LiClMag2-1.phsave/dynmat.1.100.xml and _ph1/LiClMag2-1.phsave/dynmat.1.100.xml) are almost identical, and the calculation lasted more than it should have (each of the 4 separate images has computed more than 141 representations, which is one quarter of the total). So as far as I understand it, all the images made electric field calculation and started making the same phonon mode calculations in parallel. > In this case, since you stopped the calculation, you can only > collect the .xml files in a single _ph0 directory and restart without > images. The restart with images is still poorly supported. I would like to restart without -nimage (since it seems to fail in this particular case), but with grid splitting. Do you think this is presomptuous? By the way, I had a positive experience restarting with -nimage on another run (at q neq 0) . > In the last version of QE, the dielectric constant and effective charges > are saved in the tensors.xml file in the _ph0 directory. Thank you very much for your help! Best regards, -- Merlin Méheut, Géosciences et Environnement Toulouse, OMP, 14 avenue Edouard Belin, 31400 Toulouse, France phone +33 (0)5 61 33 26 17, fax +33 (0)5 61 33 25 60 _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
