[Pw_forum] phonon calculations do not converge

[Matthijs Mentink]

Hi Iyad,

Have you considered introducing some broadening in the pwscf calculation?
It helps. Be careful not to go overboard though. You could try introducing
some broadening (like 1e-3 Ry or so) and see if it converges. If that works
than you can see how far you can reduce broadening while still having the
phonon calculations converge.

cheers,

Matthijs

On Wed, Aug 15, 2012 at 10:27 AM, Iyad AL-QASIR <iyad.ne at gmail.com> wrote:

> Hi Wiliam,
>
> I used tr2_ph = 1.0d-10, it did not converge either after 100 steps. The
> |ddv_scf|^ values are about ~ E-07.
>
> However, when I used tr2_ph = 1.0d-14, the |ddv_scf|^ values are diverging
> strongly ~E+20 and even more.
>
> Kindest Regards,
>
>
>
>
> On Fri, Aug 10, 2012 at 5:16 PM, William Parker <wparker at anl.gov> wrote:
>
>> Hi Iyad,
>>
>> How strong is the failure to converge at (0, 1/6, 1/6)?  Perhaps a less
>> tight tr2_ph value of, say, 1.0d-10 would get you where you need to be.
>>
>> --William
>>
>> On Aug 10, 2012, at 12:29 PM, Iyad AL-QASIR wrote:
>>
>> > Dear PW_Forum,
>> >
>> > I am running phonon calculations for FeSi (a narrow band gap
>> semiconductor) using QE-5.0. I am using a 6x6x6 q-vectors mesh. The first 4
>> q-points ran successfully and got good phonon values. However when I reach
>> the 5th point(0 1/6 1/6). The self-consistent calculations do not converge.
>> I tried to reduce alpha_mix(1) to 0.3 but still have the same problem.
>> >
>> > Below are my input files:
>> >
>> > &control
>> >  calculation='scf',
>> >  restart_mode='from_scratch',
>> >  title='FeSi',
>> >  outdir='./',
>> >  prefix='FeSi',
>> >  pseudo_dir='./',
>> > /
>> > &system
>> >  ibrav=1,
>> >  celldm(1)=8.4165,
>> >  nat=8, ntyp=2,
>> >  ecutwfc=60.0,
>> >  ecutrho= 720.0,
>> > /
>> > &electrons
>> >  conv_thr=1.0d-9,
>> >  mixing_mode='plain',
>> >  mixing_beta=0.7,
>> >  diagonalization='david',
>> > /
>> > ATOMIC_SPECIES
>> > Fe 55.847 Fe.pw91-sp-van_ak.UPF
>> > Si 28.086 Si.pw91-n_van.UPF
>> > ATOMIC_POSITIONS
>> > Fe 0.134855265   0.134855265   0.134855265
>> > Fe 0.634855265   0.365144735   0.865144735
>> > Fe 0.865144735   0.634855265   0.365144735
>> > Fe 0.365144735   0.865144735   0.634855265
>> > Si 0.839976366   0.839976366   0.839976366
>> > Si 0.339976366   0.660023634   0.160023634
>> > Si 0.160023634   0.339976366   0.660023634
>> > Si 0.660023634   0.160023634   0.339976366
>> > K_POINTS {automatic}
>> > 10 10 10  0 0 0
>> > ***********************************
>> > phonons of FeSi
>> >  &inputph
>> >   tr2_ph=1.0d-14,
>> >   prefix='FeSi',
>> >   amass(1)=55.847,
>> >   amass(2)=28.086,
>> >   outdir='./'
>> >   fildyn='FeSi.dyn',
>> >   trans=.true.,
>> >   ldisp=.true.,
>> >   nq1=6, nq2=6, nq3=6
>> >   recover=.true.,
>> >   alpha_mix(1)=0.30
>> >
>> > Any comments and suggestions are welcomed.
>> >
>> > Thanks
>> > IYAD
>> >
>> >
>> > _______________________________________________
>> > Pw_forum mailing list
>> > Pw_forum at pwscf.org
>> > http://www.democritos.it/mailman/listinfo/pw_forum
>>
>> *********************************************************
>>   William D. Parker                 phone: (630) 252-4834
>>   Computational Postdoctoral Fellow   fax: (630) 252-4798
>>   MSD-212, Rm. C-215
>>   Argonne National Laboratory
>>   9700 S. Cass Ave.
>>   Argonne, IL 60439
>> *********************************************************
>>
>>
>>
>>
>>
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>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>>
>
>
>
> --
> ___________________________
> IYAD I. AL-QASIR, PhD
> Postdoc Research Associate
>
> X-Ray and Neutron Scattering and Spectroscopy Group
> Materials Science and Technology Division
> Oak Ridge National Lab
> Oak Ridge, TN
>
>
> _______________________________________________
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>
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