Hello Andrea, I am not using 5.0.3 patch to QE 5.0.2 right now and I guess this is the issue. I will try using it today and will see how things go.
Thanks a lot, Ankit Jain On Mon, Apr 14, 2014 at 3:24 AM, Andrea Dal Corso <dalcorso at sissa.it> wrote: > Did you apply the 5.0.3 patch to QE 5.0.2? Without the patch, the phonon > code gives wrong frequencies for some q points. > > HTH, > > Andrea > > > On Mon, 2014-04-14 at 01:19 -0400, ankit jain wrote: > > Hello Sanjeev, > > > > The pseudopotentials I am using are > > H.pz-vbc.UPF< > http://www.quantum-espresso.org/wp-content/uploads/upf_files/H.pz-vbc.UPF> > > and C.pz-vbc.UPF< > http://www.quantum-espresso.org/wp-content/uploads/upf_files/C.pz-vbc.UPF> > > > > > > Pseudopotential type: NORMCONS > > Method: Von Barth-Car (direct fit) > > Functional type: Perdew-Zunger (LDA) exch-corr > > scalar relativistic > > > > > > I have tried kgrid of 1*1*6 and 1*1*12, but both give negative > frequencies. > > > > > > > > On Mon, Apr 14, 2014 at 12:18 AM, Sanjeev Gupta > > <physics.skgupta at gmail.com>wrote: > > > > > what is kind of pseudopotential? > > > How much k-point? > > > > > > > > > wishes > > > sanjeev > > > > > > > > > On Sun, Apr 13, 2014 at 9:25 AM, Ankit <ankitjain.me.iitk at gmail.com > >wrote: > > > > > >> Hello QE developers and users, > > >> > > >> I am trying to calculate phonon dispersion using ph.x and matdyn.x > > >> routines of QE and I am stuck woth negative frequencies for a while > now. > > >> > > >> I have a 1-D chain of polyethylene which has 6 atoms in the unit-cell. > > >> The polymer chain is aligned in z-direction and I have added vacuum on > > >> x- and y- direction. I did the structure relaxation and I am getting > > >> total force after relaxtion as 0.000020, which I guess is sufficiently > > >> small. > > >> > > >> After relaxation, when I am trying to calculate phonon dispersion > using > > >> ph.x and matdyn.x I am getting netting frequencies for some of the > > >> phonon modes. I searched online and on QE mailing list and tried > couple > > >> of different things: > > >> > > >> 1. The negative frequencies are appearing for non-gamma point as well, > > >> so I guess its not a ASR issue. Anyway, I am using ASR but even after > > >> this I am getting negative frequencies. > > >> 2. I reduced my tr2_ph and conv_thr to 1.0d-14 and 1.0d-15 which I > guess > > >> are very small as suggested on QE FAQs. > > >> 3. I checked phonon mode shapes for modes with negative frequencies > and > > >> they do not look like rotational mode. > > >> 4. I tried changing number of k points from 6 to 12 in z direction but > > >> this is also not the cause. > > >> > > >> I am really stuck here and not sure about the cause of negative > > >> frequencies. With vc-relax, my structure is getting relaxed which I > > >> guess means my structure is stable. But then I am not sure why I am > > >> getting negative frequencies. > > >> > > >> I really appreciate any help or suggestions. > > >> > > >> Thanks, > > >> > > >> Ankit Jain > > >> IIT Indore, > > >> Indore, > > >> India > > >> > > >> > > >> _______________________________________________ > > >> Pw_forum mailing list > > >> Pw_forum at pwscf.org > > >> http://pwscf.org/mailman/listinfo/pw_forum > > >> > > > > > > > > > > > > -- > > > With Best Regards, > > > > > > ------------------------------------ > > > Dr. Sanjeev Kumar Gupta > > > Fulbright Post-Doctoral Scholar > > > Dept. of Physics > > > Michigan Technological University > > > 1400 Townsend Drive, Houghton > > > MI 49931, USA > > > ------------------------------------ > > > > > > _______________________________________________ > > > Pw_forum mailing list > > > Pw_forum at pwscf.org > > > http://pwscf.org/mailman/listinfo/pw_forum > > > > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://pwscf.org/mailman/listinfo/pw_forum > > -- > Andrea Dal Corso Tel. 0039-040-3787428 > SISSA, Via Bonomea 265 Fax. 0039-040-3787249 > I-34136 Trieste (Italy) e-mail: dalcorso at sissa.it > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140414/78d9f1e6/attachment.html
