[Pw_forum] pbe normconserving pseudopotentials for Fe

[Ludwig, Stephan]

Hi Nicola,



thank you very much with this pseudopotential the ecutwfc does converge.

But I receive warnings in the output files:

warning symmetry operation # 4 not compatible with FFT grid.

This appears for 8 symetry operations.

As far as I understand this is not a huge problem but it means a time-consuming calculation.

It is recommended that I should try to increase ecutrho to get rid of this warning, but it does not vanisch even not for ecutrho=1600

Do you know why that is the case?



Thanks and Regards



Stephan



-----Original message-----
From: Nicola Marzari <nicola.marzari at epfl.ch>
Sent: Wednesday 15th April 2015 14:44
To: PWSCF Forum <pw_forum at pwscf.org>
Subject: Re: [Pw_forum] pbe normconserving pseudopotentials for Fe


My suggestion would be to use the Gygi pseudopotential at 140 Ry of cutoff.

You can find it here: http://www.quantum-simulation.org

nicola

On 15/04/2015 13:58, Ludwig, Stephan wrote:
> Hi,
>
> i want to do scf calculations on BaFe2As2. In order to find a suitable
> ecutwwc I look for a convergency for
>
> the total energy with respect to the ecutwfc.
>
> Using an ultrasoft pseudopotential for iron (Fe.pbe-nd-rrkjus.UPF) I
> achieved convergency without problems.
>
> Unfortunately I whant to use the Yambo program to calculate linear
> response. Therefore I need to use Normconserving Pseudos.
>
> By using the normconserving pseudo Fe.pbe-sp-mt_gipaw.UPF I can't
> achieve convergency, even not at ecutwfc of 460 (although I use the
> kgrid 8 8 8).
>
> I used this Pseudopotential already to simulate CaFe2As2. In this case I
> achieved convergency (but it was on another computer) but with a huge
> ecutwfc of 260.
>
> What's wrong with this Pseudopotential? Why is it not suitable?
>
>
> Whould it be a better idea to use the Normconserving pseudo
> Fe.pbe-mt_fhi.UPF? The Pseudopotential Fe.pbe-sp-hgh.UPF would not be
> suitable since also I whant to have PDOS.
>
> Here you see my input-file
>
>
>
> &CONTROL
> title = 'BaFe2As2_20K' ,
> calculation = 'scf' ,
> wf_collect = .false. ,
> outdir = './' ,
> wfcdir = './',
> pseudo_dir = '/home/espresso-5.1/pseudo/' ,
> prefix = 'BaFe2As2_20K' ,
>
> /
> &SYSTEM
> ibrav = 10,
> A = 5.5742 ,
> B = 5.6146 ,
> C = 12.9453 ,
> cosAB = 0 ,
> cosAC = 0 ,
> cosBC = 0 ,
> nat = 5,
> ntyp = 3,
> ecutwfc = 460 ,
> occupations = 'smearing' ,
> degauss = 0.02 ,
> smearing = 'gaussian' ,
> exxdiv_treatment = 'gygi-baldereschi' ,
> /
> &ELECTRONS
> conv_thr = 1.0D-8 ,
> /
> ATOMIC_SPECIES
> Ba 137.33000 Ba.pbe-mt_fhi.UPF
> Fe 55.84700 Fe.pbe-sp-mt_gipaw.UPF
> As 74.92200 As.pbe-hgh.UPF
> ATOMIC_POSITIONS angstrom
> Ba 0.000000000 0.000000000 0.000000000
> Fe 1.393550000 1.403650000 3.236325000
> Fe 1.393550000 4.210950000 3.236325000
> As 0.000000000 0.000000000 4.580047140
> As 0.000000000 0.000000000 8.365252860
> K_POINTS automatic
> 8 8 8 0 0 0
>
>
>
> Thanks and Regards
>
>
> Stephan
>
>
>
>
> _______________________________________________
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> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
-- 

----------------------------------------------------------------------
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
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