Dear Daniel, Stefano and Paolo. My added penny: in my hands US/EXX has never worked in a useful way...:-( Moreover there is a nasty constraint that force ecutrho=4*ecutwfc, that is not exactly the best for US PPs. It might turn out that a NC/EXX calculation (always very satisfying in my hands) is significantly faster end quite reliable, even if you must use 80/320 Ry cutoffs (or even higher; first row transition metals with 2s,2p semicore electrons are usually the hardest NC PPs).
You can try to speedup the calculation by using a) adaptive_thr=.true. In the case of smooth convergence this makes inner scf cycles significantly faster. b) ecutfock~[1/2-->1/4]*ecutrho Fantastic with isolated systems; handle with care with metals because this might change occupations at k-points. You should check convergence on this, but in the case of "almost metallic" systems (e.g., shallow defects in semiconductors) ecutfock=1/2*ecutrho is often well converged. c) remember that (at least in principle) you should check convergence with respect to the projection of density in real space: you are (implicitly) using one q-point for each k-point, having not assigned any value to nqx1, nqx2, nqx3. More q points increase the computational effort. You might try to reduce the k grid and to increase nqx(i) values to find a correct balance: However a 7 7 7 0 0 0 grid is actually large. You will not be able to perform 'nscf' or 'bands' calculations to have a proper band structure, and densities/forces/stresses/eigenvalues/energies should converge at an acceptable level with less k points. HTH Giuseppe On Friday, September 09, 2016 10:42:49 AM Daniel Stoeffler wrote: > Hello Stefano, > > As said, I am a new user of QE but not of the DFT > ;). I use the FLEUR, Abinit and the VASP codes and I want to test if it > would be interesting for my studies to use also QE. > > I said > "surprisingly" huge because I compared to the VASP code with the same > parameters (Ecutoff, NKpoints, Nq) and with the HSE functional. Indeed, > with the VASP code during one night on my computer I got a few tens of > iterations compared to one with QE :(. > > >From my point of view, I > > compare 2 pseudopotential-based methods for the same parameters which I > can control via the input file : my question would then more preferably > be "which default parameter should I modify to make the QE calculation > time similar to the VASP one ?" > > Best wishes, > > Daniel > > Le 2016-09-09 > > 09:47, Stefano de Gironcoli a écrit : > > Please read the literature > > about hybrid functionals in plane waves; understand why the > computational time is, not unexpectedly, huge and start think about it. > > > If you come up with some smart idea on how to reduce the > > computational time without compromising accuracy (as for the ACE > transformation recently proposed by Lin Lin and implemented in the > latest QE version) let us know > > > Best, > > stefano > > (sent from my phone) > > > > > > On 09 Sep 2016, at 09:30, Daniel Stoeffler > > <[email protected]> wrote: > >> Hello, > >> > >> As a new > > QE user, I do some tests with the HSE Functional for BCC ferromagnetic > Fe with a cell containing 2 atoms (because a want to go to CoFe after > that). > > >> My input file is : > >> > >> &control > >> title='Fe CC > > HSE', > > >> calculation = 'scf', > >> prefix = 'Fe_CC_HSE', > > pseudo_dir='./', > > >> verbosity = 'high' > >> / > >> &system > >> ibrav = 6, > > celldm(1) = 5.45, > > >> celldm(3) = 1.0, > >> nat = 2, > >> ntyp = 1, > > nspin = 2, > > >> occupations='smearing', smearing='gauss', degauss=0.01, > > starting_magnetization(1) = 1.0, > > >> ecutwfc = 33, > >> input_dft='HSE', > >> > >> report = 5 > >> / > >> &electrons > >> mixing_beta = 0.7 > >> / > > ATOMIC_SPECIES > > >> Fe 55.845 Fe.pbe-sp-van.UPF > >> > >> ATOMIC_POSITIONS > > (crystal) > > >> Fe 0.000 0.000 0.000 > >> Fe 0.500 0.500 0.500 > > K_POINTS (automatic) > > >> 7 7 7 0 0 0 > >> > >> Surprisingly, the computation > > time is huge as writen into the output file : > > > =============================== > > >> iteration # 9 ecut= 33.00 Ry > > beta=0.70 > > >> Davidson diagonalization with overlap > >> ethr = 5.49E-08, > > avg # of iterations = 2.3 > > >> Magnetic moment per site: > >> atom: 1 > > charge: 14.4350 magn: 2.6346 constr: 0.0000 > > >> atom: 2 charge: 14.4351 > > magn: 2.6343 constr: 0.0000 > > >> total cpu time spent up to now is 7.2 > > secs > > >> End of self-consistent calculation > >> > >> convergence has > > been achieved in 9 iterations > > >> EXX: now go back to refine exchange > > calculation > > >> total cpu time spent up to now is 4239.4 secs > > Self-consistent Calculation > > >> iteration # 1 ecut= 33.00 Ry > > beta=0.70 > > >> Davidson diagonalization with overlap > >> ethr = 5.49E-08, > > avg # of iterations = 4.9 > > >> total cpu time spent up to now is > > 52490.2 secs > > >> iteration # 2 ecut= 33.00 Ry beta=0.70 > >> Davidson > > diagonalization with overlap > > >> =============================== > >> > >> > >> So, the calculation takes 7 seconds for converging with PBE, 1h10min > > for calculating the EXX term and 14h35min for the first HSE iteration. > Is this correct ? And if so, please, could you try to explain me how to > reduce the computation time. Thanks in advance. > > >> Best wishes, > >> > >> > >> Daniel > >> > >> _______________________________________________ > > Pw_forum mailing list > > >> [email protected] > > http://pwscf.org/mailman/listinfo/pw_forum [1] > > > _______________________________________________ > > > Pw_forum mailing > > list > > > [email protected] > > http://pwscf.org/mailman/listinfo/pw_forum > > [1] > > > Links: > ------ > [1] http://pwscf.org/mailman/listinfo/pw_forum ******************************************************** - Article premier - Les hommes naissent et demeurent libres et égaux en droits. Les distinctions sociales ne peuvent être fondées que sur l'utilité commune - Article 2 - Le but de toute association politique est la conservation des droits naturels et imprescriptibles de l'homme. Ces droits sont la liberté, la propriété, la sûreté et la résistance à l'oppression. ******************************************************** Giuseppe Mattioli CNR - ISTITUTO DI STRUTTURA DELLA MATERIA v. Salaria Km 29,300 - C.P. 10 I 00015 - Monterotondo Stazione (RM), Italy Tel + 39 06 90672342 - Fax +39 06 90672316 E-mail: <[email protected]> http://www.ism.cnr.it/en/staff/giuseppe-mattioli/ ResearcherID: F-6308-2012 _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
