Hello Paolo,
Thank you for your answer. Up to now, I used the FLEUR, Abinit and the VASP codes and I am doing some tests to see if it would be interesting (or not) for my studies to use also QE. I found the computation "surprisingly" huge because when I compare to the VASP code with the same parameters (Ecutoff, NKpoints, Nq) and with the HSE06 functional, after onr night of run, I got a few tens of iterations whereas I got only one with QE :(. For these tests, I compare 2 pseudopotential-based methods for the same parameters which I can control via the input file (Ecutoff and Kpoints). I have compared the (defaut) q-points and they are identical for the VASP and the QE codes. I will try the "tqr=.true." option and let you know. Concerning the Pseudopotential, I decided to use Fe.pbe-sp-van.UPF in order to keep the Ecutoff small : I tried HGH but the Ecutoff needed for magnetic systems is very large and I have avoided to use NLCC pseudopotentials which are not compatible with hybrid functional (is this correct ?). The final system I would investigate is the Fe(FeCo)O4 spinel with a 28-atoms into cell using hybrid functionals : from your experience and knowlege, it this hopeless with QE or not ? Best wishes, Daniel Le 2016-09-09 10:21, Paolo Giannozzi a écrit : >> The computational complexity of a calculation with hybrid functionals goes as (Nk*Nb)^2*Npw log(Npw) or so, where Nk=number of k-points, Nb=number of occupied bands, Npw=number of plane waves; with GGA functionals, as Nk*Nb*Npw log(Npw) or Nk*Nb*Npw^2 > > well, no, as Nk*Nb*Npw log(Npw) or Nk*Nb^2*Npw > > Paolo > >>> could you try to explain me how to reduce the computation time >> >> first of all you may try to reduce one of the sums over k-points using options nq1,nq2,nq3, as explained in the example for hybrid. For a metal, not sure it works well, though. Since you are using UltraSoft PseudoPotentials, try option "tqr=.true." (real-space treatment of augmentation functions): it should give a significant speedup. Another significant improvement is contained in the forthcoming 6.0 version of QE, but it doesn't work yet for USPP >> >> Paolo -- >> >> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, >> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy >> Phone +39-0432-558216 [1], fax +39-0432-558222 [2] > > -- > > Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, > Univ. Udine, via delle Scienze 208, 33100 Udine, Italy > Phone +39-0432-558216, fax +39-0432-558222 > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum [3] Links: ------ [1] tel:%2B39-0432-558216 [2] tel:%2B39-0432-558222 [3] http://pwscf.org/mailman/listinfo/pw_forum
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