There is a problem with reduced-cutoff calculations (using ecutfock < 4*ecutwfc) and k-points. Thank you for reporting this
Paolo On Mon, Aug 28, 2017 at 8:33 AM, Prasenjit Ghosh <[email protected]> wrote: > Dear all, > > We are doing calculations for my system (PbI2) with hybrid functionals > (using the ACE algorithm) and norm conserving pseudopotentials. Presently > we are performing this calculations using scalar relativistic > non-conserving pseudopotentials for Pb and I. The pseudopotentials have > been generated by me using PBE functionals. I have tested these (at the > level of GGA) and it can reproduce well the lattice parameters and > electronic bandstructure of a range of different compounds (from metallic > Pb to ionic PbI2 and CsPbBr3). > > When we perform the hybrid calculations using GAU-PBE, we find that the > total energy differs when we use 1 core and 4 cores. The energy difference > is about 0.23 Ry. However, for both the cases, the standard GGA-PBE > calculations give same results (total energy). Even the band gap with > GAU-PBE (using 1 and 4 cores) are same. A look into the output file > suggests that the difference comes from > -averaged Fock potential + Fock energy. > > Since I have generated the pseudopotential, I thought that there might be > some issue with this. Hence to cross check, I downloaded the normconserving > pseudopotentials for Pb and I from http://theossrv1.epfl.ch/Main/ > Pseudopotentials (pbe.0.3.1.tgz). For these two pseudopotentials also the > total energies (1 core vs 4 cores) differ. The input files, pseudopotential > files and the output files can be downloaded from the link given below: > > http://www.iiserpune.ac.in/~pghosh/QE/ > > These results are reproducible on different machines, using different > compilers (eg. gfortran vs intel). > > I think that there is a bug in the code, particularly the part where the > contributions to total energy from EXX is collected. If the developers can > suggest where exactly to look for in the code, I can give it a try to sort > it out. > > With regards, > > Prasenjit. > > -- > PRASENJIT GHOSH, > IISER Pune, > Dr. Homi Bhabha Road, Pashan > Pune, Maharashtra 411008, India > > Phone: +91 (20) 2590 8203 <+91%2020%202590%208203> > Fax: +91 (20) 2589 9790 <+91%2020%202589%209790> > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- 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
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