[Pw_forum] Slow convergence of Fe-111 surface by QE

[Narendranath Ghosh]

Thank you Ashkan  and  A P Seitsonen. it works with high  Ecutwfc and very
low mixing parameter.



Best regards,

Naren

*Dr. Narendra Nath Ghosh*

*Research Associate*

*University of Gour Banga*

*Department of Chemistry*

*Malda-732102*

*India*

*Phone: +919126667601*

On Fri, May 5, 2017 at 1:14 PM, Ari P Seitsonen <Ari.P.Seitsonen at iki.fi>
wrote:

>
> Dear Naren,
>
>   In addition to the (much) too low cut-off energy you wrote that you
> tried several parametres, but it is difficult to us to guess for what you
> tried: Clearly now there is no spin polarisation, the mixing parametre is
> probably much too large, the 'degauss' too small (personally I prefer the
> Fermi-Dirac broadening), is the system ferromagnetic, why 'nosym =
> .true.'...? Please try a systematic approach, starting from most "physical"
> values for the parametres and then try to switch to something simpler,
> trying to understand for what goes wrong.
>
>     Greetings,
>
>        apsi
>
> -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=
> -=*=-=*=-=*=-=*=-
>   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
>     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
>     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935
>
>
>
> On Fri, 5 May 2017, Narendranath Ghosh wrote:
>
> Dear all!
>>
>> I am currently trying to optimize a Fe-111 surface.But I find very slow
>> convergence even after 229
>> iteration it didn't get converged.I have changed some parameters
>> like smearing , degauss
>> ,nspin, K_POINTS but nothing happened.
>> Input
>>  &CONTROL
>>   calculation='relax',
>>   outdir='/share_home/hpc/BONS_QE/Fe-111/OUTPUT',
>>   prefix='Fe-111',
>>   pseudo_dir='/share_home/hpc/BONS_QE/pseudo',
>>   verbosity='low',
>>   nstep=500,
>> /
>>
>> &SYSTEM
>>   ibrav=0,
>>   celldm(1)=22.9819600668d0,
>>   nat=81,
>>   ntyp=1,
>>   ecutwfc=30.0d0,
>>   input_dft='PBE',
>>   nosym = .true.,
>>   occupations='smearing',
>>   smearing='mv',
>>   degauss=0.005000d0,
>>   starting_magnetization(1)=0.5
>>
>>
>> /
>>
>> &ELECTRONS
>>   mixing_mode='local-TF',
>>   mixing_beta=0.700d0,
>>   electron_maxstep=500,
>> /
>>
>> &IONS
>> /
>>
>> ATOMIC_SPECIES
>>   Fe 55.845000d0 Fe.pbe-mt_fhi.UPF
>>
>> ATOMIC_POSITIONS {alat}
>> Fe       0.166666360   0.096224929   1.432718760
>> Fe       0.499999991   0.096224958   1.432718812
>> Fe       0.833333491   0.096224719   1.432718553
>> ....................................................................
>>
>> K_POINTS {automatic}
>> 3 3 1 0 0 0
>> CELL_PARAMETERS {alat}
>>   1.000000000000d0  0.000000000000d0  0.000000000000d0
>>   -0.500000000000d0  0.866025403784d0  0.000000000000d0
>>   0.000000000000d0  0.000000000000d0  3.339792528637d0
>>
>>
>> ...
>>
>>
>> Any comment to help me getting started is very much appreciated!
>>
>>
>>
>> Best regards,
>>
>> Naren
>>
>>
>>
>>
>>
>> Dr. Narendra Nath Ghosh
>> Research Associate
>> University of Gour Banga
>> Department of Chemistry
>> Malda-732102
>> India
>> Phone: +919126667601
>>
>
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