[QE-users] Phonon calculation does not converge

[Chirantan Pramanik]

Hello Lorenzo Paulatto and Nicola Marzari,

I performed relax and scf both with the prescribed cutoff as discussed in the previous mail and now I am running phonon. I am trying to increase the 'nmix_ph' to 16 as I have more memory available in the server, but the error says, 'Error in routine phq_readin (1): Wrong nmix_ph'.  I checked online where 'https://lists.quantum-espresso.org/pipermail/users/2015-October/033664.html' Prof. Paolo Giannozzi said to keep it below 5, but in 2015. So what is going on?  Please help, I never included nmix_ph before, but using more memory and speeding up the phonon calculation will help me a lot.

Regards,
Chirantan
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Lorenzo Paulatto <lorenzo.paulatto at cnrs.fr>
Sent: Tuesday, January 23, 2024 10:02 AM
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] Phonon calculation does not converge


The calculation is not only not converging, it is actually diverging. Changing alpha_mix and increasing nmix_ph can help, but it may also indicate something wrong with the calculation. I.e. a metal treated as semiconductor, or a ghost in the pseudopotential (which may be likely if you use norm-conservig cutoff with an ultrasoft dataset)

hth


On 1/23/24 08:47, Chirantan Pramanik wrote:
Hello All,

I was running Phonon for a few systems of carbonate minerals for a long time. Recently I used SSSP pseudopotential for PBE and faced a problem like the one pasted below. Optimization and SCF calculations are properly done. But phonon calculation is not converging. Please help. I think changing alpha_mix can be useful, but for my stable and optimized system, it should converge easily.

section from ph.x output:

      iter #  97 total cpu time :  1799.1 secs   av.it.:  84.0
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  1.595E+08

      iter #  98 total cpu time :  1822.7 secs   av.it.:  92.0
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  3.870E+10

      iter #  99 total cpu time :  1846.5 secs   av.it.:  92.0
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  4.585E+10

      iter # 100 total cpu time :  1869.3 secs   av.it.:  88.0
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  5.897E+09

     End of self-consistent calculation

     No convergence has been achieved


Please help in this regard.

Thanks and Regards,
Chirantan

Chirantan Pramanik
Postdoctoral Researcher
Dept. of Earth and Planetary Sciences
Weizmann Institute of Science
Rehovot, Israel



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