Thanks a lot Andrea. I just checked it and it solved the issue. Frequencies are all non-negative now.
Thank You, Ankit Jain On 04/14/2014 03:24 AM, Andrea Dal Corso 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
