[Pw_forum] pbe normconserving pseudopotentials for Fe

[Paolo Giannozzi]

Set the FFT grid to a value that is commensurate with your 
fractional translation, or set option "use_all_frac" to T
if you do not plan to perform phonon calculations

Paolo

On Thu, 2015-04-16 at 15:00 +0200, Ludwig, Stephan wrote:
> 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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>         >
>         -- 
>         
>         ----------------------------------------------------------------------
>         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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-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222