[QE-users] Phonon calculation does not converge

[Lorenzo Paulatto]

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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