Dear Stefano Thanks for your mail. But what does this error mean? when I try to run the calculation, it ejects this error? How can I get rid of it Error in routine setup (1): Variable cell and EXX not tested! The input file is as under
&CONTROL title = 'CsPbI' , calculation = 'vc-relax' , restart_mode = 'from_scratch' , outdir = '/work/saqlain' , wfcdir = '/work/saqlain' , pseudo_dir = '/home/ibm/proj/proj527/saqlain/psp' , prefix = 'PBE0' , / &SYSTEM ibrav = 0, celldm(1) = 1.8897265, nat = 5, ntyp = 3, ecutwfc = 40 , input_dft = 'PBE0' , occupations = 'smearing' , degauss = 0.001 , smearing = 'marzari-vanderbilt' , ecutfock = 40 , exxdiv_treatment = 'none' , nqx1 = 2 , nqx2 = 2 , nqx3 = 2 , / &ELECTRONS / &IONS / &CELL / CELL_PARAMETERS cubic 6.382434987 0.000000000 0.000000000 0.000000000 6.382434987 0.000000000 0.000000000 0.000000000 6.382434987 ATOMIC_SPECIES Cs 132.90000 Cs.pbe-sp-hgh.UPF I 126.90000 I.pbe-hgh.UPF Pb 207.20000 Pb.pbe-hgh.UPF ATOMIC_POSITIONS crystal Cs 0.500000000 0.500000000 0.500000000 I 0.500000000 0.000000000 0.000000000 I 0.000000000 0.500000000 0.000000000 I 0.000000000 0.000000000 0.500000000 Pb 0.000000000 0.000000000 0.000000000 K_POINTS automatic 2 2 2 1 1 1 On Sat, Jul 23, 2016 at 6:48 PM, stefano de gironcoli <degir...@sissa.it> wrote: > On 23/07/2016 14:23, Muhammad Adnan Saqlain wrote: > > Dear Stefano > thanks for your response. > Can you please guide me (1) Why vc-relax is not allowed in Q-E 5.4.0? > > it is. > > (2) How would the band gap be effected if I relax the cell without hybrid > scheme and then calculate band gap with hybrid one? > > it would be the band gap of a different structure. > it would depend on how different the structure would be with a different > functional. > > stefano > > > On Sat, Jul 23, 2016 at 1:07 PM, stefano de gironcoli <degir...@sissa.it> > wrote: > >> dear Muhammad Adnan Saqlain, >> >> gamma extrapolation is a way to deal with the ill defined value of the >> exchange integral between wfcs at k and k+q in the limit of q->0. >> if you use a truncated coulomb interaction that limit is not ill >> defined. >> no need to use the gamma_extrapolation option >> best, >> stefano >> >> On 23/07/2016 10:00, Muhammad Adnan Saqlain wrote: >> >> Dear Prof Clavijo >> I am extremely sorry for my misleading title of the calculation. >> Actually, It was a cubic structure consisting of Cs, Pb and I. I >> deliberately did not put the atoms in the calculation. more over I do not >> know why the algorithm for cell movement was not copied it was however >> present in the input file. >> >> 1. If I try these two options, the >> >> vcut_spherical : appropriate for cubic and quasi-cubic supercells >> vcut_ws : appropriate for strongly anisotropic supercells, see also >> ecutvcut. >> >> the program says like this >> >> >> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% >> Error in routine system_checkin (1): >> x_gamma_extrapolation cannot be used with vcut >> >> >> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% >> >> I have no idea how to fix it. Can you suggest one?? >> >> 2. I have now used Q-E 5.4.0, but this version does not allow vc-relax >> option with hybrid one. why is it so? How would the band gap be effected if >> I relax the cell without hybrid scheme and then calculate band gap with >> hybrid one? >> >> 3. About the ecutoff, I deliberately used small one as these are just >> calculations not the real one. >> 4. I have cubic system, may I try q-grid like 1*2*3 or it has to be >> symmetric one? >> 5. Can you suggest more about hybrid calculations? >> >> >> On Fri, Jul 22, 2016 at 10:09 PM, Josue Itsman Clavijo Penagos < >> jiclavi...@unal.edu.co> wrote: >> >>> Dear, Muhammad Adnan Saqlain, remember the user documentation for >>> *exxdiv_treatment*: >>> >>> Specific for EXX. It selects the kind of approach to be used >>> for treating the Coulomb potential divergencies at small q vectors. >>> >>> gygi-baldereschi : appropriate for cubic and *quasi-cubic supercells* >>> vcut_spherical : appropriate for cubic and quasi-cubic supercells >>> vcut_ws : appropriate for strongly anisotropic supercells, see also >>> ecutvcut. >>> none : sets Coulomb potential at G,q=0 to 0.0 (required for GAU-PBE) >>> >>> *Besides that, *I have some observations and suggestions for you based >>> in the input file you send, so you can realize why does QE is failing when >>> trying to simulate your system: >>> >>> 1 - Check if you really need to apply smearing, since this technique is >>> intended to be useful for metallic systems, and Anatase is cleary not a >>> metallic system, in fact, is more a Wide-gap or Insulator -type system. >>> >>> 2 - You do want to perform a vc-relax calculation, but nothing are >>> specified in the cards &IONS and &CELL. There is not cell relaxing >>> algorithm specified (BFGS? MD?) >>> >>> 3 - The card &ATOMIC_POSITIONS shows nothing: No atoms, no cell to relax. >>> >>> 4 - In the card &SYSTEM , *ecutwfc = 40.* This, in my humble opinion, a >>> very poor cutoff for a serious calculation. Do a ecutwfc convergence test >>> before attempt your system. >>> >>> 5 - Please take in account that a hybrid calculation is VERY expensive >>> in terms of computational demand, so if you set up a vc-relax calculation >>> using hybrid PPS you must test if *nqx1 = 1, 2 or 3 really makes a >>> difference.* >>> >>> *6 - For some systems, input_dft=HSE is faster than **input_dft = >>> "PBE0". Check if that could be your case.* >>> >>> By the way, are you sure Anatase has a cubic crystal structure? Does >>> XCrysden show the correct structure for your input? >>> >>> *Best regards, * >>> >>> >>> Josué Clavijo, PhD. >>> Assistant Professor >>> Universidad Nacional de Colombia >>> Departamento de Química >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum@pwscf.org >>> http://pwscf.org/mailman/listinfo/pw_forum >>> >> >> >> >> -- >> Best Regards >> Muhammad Adnan Saqlain >> >> >> >> _______________________________________________ >> Pw_forum mailing >> listPw_forum@pwscf.orghttp://pwscf.org/mailman/listinfo/pw_forum >> >> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum@pwscf.org >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > > -- > Best Regards > Muhammad Adnan Saqlain > > > > _______________________________________________ > Pw_forum mailing > listPw_forum@pwscf.orghttp://pwscf.org/mailman/listinfo/pw_forum > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum@pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -- Best Regards Muhammad Adnan Saqlain
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