Dear Giuseppe, Indeed I tried with different exxdiv_treatment methods except the one which allows to manually set the ecutvcut cutoff (vcut_ws), since I read somewhere that it can be useful only in the case of strongly anisotropic cells and in non-bulk systems. I can try though. Instead I didn't try with different PPs, that's a good idea. Thanks for your help!
Ciao, Matteo > Il giorno 29/nov/2013, alle ore 19:01, Giuseppe Mattioli <giuseppe.mattioli > at ism.cnr.it> ha scritto: > > > Dear Matteo > Did you also try to play a bit with different exxdiv_treatment methods > (with different ecutvcut cutoffs) and/or different PPs? > Ciao > Giuseppe > > Quoting Matteo Gerosa <mgerosa88 at gmail.com>: > >> Dear Giuseppe, >> >> thanks for your answer. I'm using the 5.0.2 version of QE plus 5.0.3 >> patches. I'm running bulk calculations on MgO (rocksalt structure). The >> problem arises only for some q-grids (in one case, also when setting the >> q-grid equal to the k-grid), but I haven't understood why. And, as I said >> before, shifting the k-grid alone solves the problem. I attach here a >> sample input file. >> >> &CONTROL >> calculation = 'scf' , >> restart_mode = 'from_scratch' , >> outdir = '/home/matteo/qe/tmp/' , >> pseudo_dir = '/home/matteo/qe/espresso-5.0.2/pseudo/' , >> prefix = 'mgo_hse06' , >> verbosity = 'default' , >> tstress = .true. , >> tprnfor = .true. , >> / >> &SYSTEM >> ibrav = 2, >> celldm(1) = 7.9594, >> nat = 2, >> ntyp = 2, >> ecutwfc = 100.0 , >> nbnd = 8 , >> input_dft = 'hse', nqx1 = 2, nqx2 = 2, nqx3 = 2, >> x_gamma_extrapolation = .true., >> exxdiv_treatment = 'gygi-baldereschi', >> / >> &ELECTRONS >> conv_thr = 1.0d-9 , >> mixing_beta = 0.7 , >> / >> &IONS >> ion_dynamics = 'bfgs' , >> / >> ATOMIC_SPECIES >> Mg 24.30500 Mg.pbe-hgh.UPF >> O 15.99940 O.pbe-mt.UPF >> ATOMIC_POSITIONS alat >> Mg 0 0 0 >> O 0.5 0.5 0.5 >> K_POINTS automatic >> 4 4 4 0 0 0 >> >> >> Thank you for your help. >> >> Matteo >> >> >> >> 2013/11/29 Giuseppe Mattioli <giuseppe.mattioli at ism.cnr.it> >> >>> >>> Dear Matteo >>> Which QE version are you using? >>> I've clashed against similar issues, introduced in the late svn >>> versions and (probably) corrected in the latest version, which were >>> not present in the stable 5.0.2 version. If you are using the stable >>> version, the problem should come out only in the case of strongly >>> anisotropic (e.g., surface slabs with large vacuum) cells. Do you find >>> it in bulk simulations (ZnO and TiO2, I suppose...:-))?. I've >>> performed EXX simulations of these two guys, in the case of bulk as >>> well as of surface cells. I did not fall into your dexx errors. >>> HTH >>> >>> Giuseppe >>> >>> Giuseppe Mattioli >>> ISM-CNR >>> Italy >>> >>> Quoting Matteo Gerosa <mgerosa88 at gmail.com>: >>> >>>> Dear all, >>>> >>>> I've been trying to calculate band gaps for some semiconductor oxides >>>> using hybrid functionals (pbe0, hse, b3lyp). >>>> I've learned the choice of the q-grid for computing the exchange energy >>>> can be critical. Indeed in some cases I cannot achieve self-consistency >>>> and an error message appears in the output file warning that the dexx >>>> correction term becomes negative. >>>> I guess this is related to the small-q divergence issue for some >>>> particular q-grid patterns. In fact, if the k-grid is shifted away from >>>> gamma (keeping the q-grid fixed) convergence is achieved. Unfortunately, >>>> this doesn't allow me to compute the gap at the gamma point, which I'm >>>> interested in. On the other hand, I also obtain convergence if I set >>>> "x_gamma_extrapolation=.false.", but this induces large errors for a >>>> small number of points in the q-grid. >>>> How is it possible to solve the problem and, more importantly, predict >>>> in which configurations of the q-grid could the problem arise? Is there >>>> any way to shift the q-grid away from gamma? >>>> >>>> Thanks for any help you can provide. >>>> >>>> Best regards, >>>> >>>> Matteo Gerosa >>>> >>>> -- >>>> Matteo Gerosa >>>> NanoLab - Micro and Nanostructured Materials Lab >>>> Department of Energy, Politecnico di Milano >>>> Via Ponzio 34/3 I-20133 Milano, Italy >>>> >>>> tel. +39 02 2399 6364 >>>> web: www.nanolab.polimi.it >>>> >>>> >>>> _______________________________________________ >>>> Pw_forum mailing list >>>> Pw_forum at pwscf.org >>>> http://pwscf.org/mailman/listinfo/pw_forum >>> >>> >>> -- >>> ******************************************************** >>> - Article premier - Les hommes naissent et demeurent >>> libres et ?gaux en droits. Les distinctions sociales >>> ne peuvent ?tre fond?es que sur l'utilit? commune >>> - Article 2 - Le but de toute association politique >>> est la conservation des droits naturels et >>> imprescriptibles de l'homme. Ces droits sont la libert?, >>> la propri?t?, la s?ret? et la r?sistance ? l'oppression. >>> ******************************************************** >>> >>> Giuseppe Mattioli >>> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA >>> v. Salaria Km 29,300 - C.P. 10 >>> I 00015 - Monterotondo Stazione (RM) >>> Tel + 39 06 90672836 - Fax +39 06 90672316 >>> E-mail: <giuseppe.mattioli at ism.cnr.it> >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://pwscf.org/mailman/listinfo/pw_forum > > > -- > ******************************************************** > - Article premier - Les hommes naissent et demeurent > libres et ?gaux en droits. Les distinctions sociales > ne peuvent ?tre fond?es que sur l'utilit? commune > - Article 2 - Le but de toute association politique > est la conservation des droits naturels et > imprescriptibles de l'homme. Ces droits sont la libert?, > la propri?t?, la s?ret? et la r?sistance ? l'oppression. > ******************************************************** > > Giuseppe Mattioli > CNR - ISTITUTO DI STRUTTURA DELLA MATERIA > v. Salaria Km 29,300 - C.P. 10 > I 00015 - Monterotondo Stazione (RM) > Tel + 39 06 90672836 - Fax +39 06 90672316 > E-mail: <giuseppe.mattioli at ism.cnr.it> > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum
