[Pw_forum] negative phonon frequencies for 1-D polymer chain

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

[Pw_forum] negative phonon frequencies for 1-D polymer chain

Did you try using the acoustic sum rule and see whether the imaginary frequencies are still there? Also can I have a look at the vc-relax output file? Prasenjit On 14 April 2014 11:10, ankit jain wrote: > Hello Prasenjit, > > I am getting negative phonon frequencies for non-gamma points also.

[Pw_forum] negative phonon frequencies for 1-D polymer chain

For which q-point are you getting the imaginary modes? If it is at gamma, then it may be related to the instability in the structure, if it is at other q-points, may be lattice parameter is not properly optimized. How large is the stress you are getting at the end of the vc-relax calculation (when

[Pw_forum] negative phonon frequencies for 1-D polymer chain

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 wrote: > Did you apply the 5.0.3 patch to QE 5.0.2? Without the

[Pw_forum] negative phonon frequencies for 1-D polymer chain

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 >

[Pw_forum] negative phonon frequencies for 1-D polymer chain

Hello Prasenjit, Please find the output file for vc-relax attached. I had rerun my calculations so this file has slightly different coordinate from what is reported in pw.in. Thanks, Ankit Jain On Mon, Apr 14, 2014 at 2:12 AM, Sanjeev Gupta wrote: > good. > can you take one more test to

[Pw_forum] negative phonon frequencies for 1-D polymer chain

I will try changing the pseudopotential and repeat the calculations. I will report back to you as sson as my calculations are finish (will probably take a day to finish structure relaxation). On Mon, Apr 14, 2014 at 2:12 AM, Sanjeev Gupta wrote: > good. > can you take one more test to change

[Pw_forum] negative phonon frequencies for 1-D polymer chain

I have tried acoustic sum rule and it does not change negative frequencies. I have rerun calculations with several different parameters and seems to have modified my vc-relax output file. I am re-running it and will send it as soon as it is done. On Mon, Apr 14, 2014 at 1:51 AM, Prasenjit Ghosh

[Pw_forum] negative phonon frequencies for 1-D polymer chain

Hello Prasenjit, I am getting negative phonon frequencies for non-gamma points also. After structure optimization, the total force is 0.20 Ry/au and pressure is -0.24 kbar. I am using ecutwfc of 100 Ry, which is converged with respect to the total energy of the system. I am not able to do

[Pw_forum] negative phonon frequencies for 1-D polymer chain

Hello Sanjeev, The pseudopotentials I am using are H.pz-vbc.UPF and C.pz-vbc.UPF Pseudopotential type: NORMCONS Method: Von Barth-Car (direct

[Pw_forum] negative phonon frequencies for 1-D polymer chain

good. can you take one more test to change the pseudo and see. May be I am wrong but see. On Sun, Apr 13, 2014 at 11:02 PM, ankit jain wrote: > I have tried acoustic sum rule and it does not change negative > frequencies. > I have rerun calculations with several different parameters and

[Pw_forum] negative phonon frequencies for 1-D polymer chain

what is kind of pseudopotential? How much k-point? wishes sanjeev On Sun, Apr 13, 2014 at 9:25 AM, Ankit 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. >

[Pw_forum] negative phonon frequencies for 1-D polymer chain (forgot to attach files in previous mail)

Please ignore my previous mail. I forgot to attach pw.in and ph.in files in my previous mail. 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

[Pw_forum] negative phonon frequencies for 1-D polymer chain

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