Re: [QE-users] Phonon calculation does not converge

[Paolo Giannozzi]

On 1/29/24 11:26, Chirantan Pramanik wrote:


'Error in routine phq_readin (1): Wrong nmix_ph'

there is no such error anywhere in the phonon code

Paolo
--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine Italy, +39-0432-558216
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Re: [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  on behalf of Lorenzo 
Paulatto 
Sent: Tuesday, January 23, 2024 10:02 AM
To: users@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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