Dear Daniel 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 :(. >
With exactly the same parameters the computational time (on one processor) should be comparable. There are two important points you should consider to make a comparison: -Different type of methodology: Using EXX with Ultrasoft pseudopotentials a very large number of augmentation charges are computed. As already suggested setting tqr=.true. should solve this problem. -If you changed the default values of some variables such as Precfock or Nkred in Vasp the computational parameters are not anymore the same in Vasp and QE. Best, Dario > 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 <daniel.stoeffler@ipcms. > unistra.fr> 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 > > > _______________________________________________ > Pw_forum mailing > [email protected]http://pwscf.org/mailman/listinfo/pw_forum > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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