[Pw_forum] SCF run not converging

[sayan chaudhuri]

Dear QE exparts,


   How to get rid of the small unit cell problem?
   When it is a pure system, Wycoff positions with Atomic positions card
set at alat works. So, is there any definite procedure to give the position
of the atoms in the system when I am doping in the system?

 Thanking you,
        Sayan Chaudhuri

On Fri, Dec 9, 2016 at 7:07 PM, Lorenzo Paulatto <
lorenzo.paulatto at impmc.upmc.fr> wrote:

> It may be difficult to converge LDA+U calculations in general, starting
> with
> initial magnetizations that aren't absurd may help
>
> hth
>
> On Friday, December 9, 2016 5:29:01 PM CET Максим Арсентьев wrote:
> > Dear Lorenzo,
> >
> > I have the same problem - cannot achieve SCF convergence. I use higher
> > ecutwfc = 39.0, ecutrho = 300 but not coverging.
> >
> > Regards, Maxim Arsentev.
> >
> > 2016-12-09 12:52 GMT+04:00 Lorenzo Paulatto <
> lorenzo.paulatto at impmc.upmc.fr>
> > > Dear Sayan,
> > > it looks to me like your unit cell is too small, the atoms are all
> crumped
> > > together.  Please note that celldm(1) is specified in bohr atomic
> units.
> > >
> > > Also:
> > > 1. a cutoff of 30Ry is probably very small for BHS pseudopotentials
> > > 2. ecutrho=default (4*ecutwfc ) is probably not enough for all the
> > > ultrasoft
> > > pseudopotentials you are using
> > >
> > > I would recommend you first spend some time reproducin the
> single-element
> > > metal, and once you can correctly reproduce geometry, band structure,
> > > physical
> > > properties, you move to simulating the alloy.
> > >
> > > HTH
> > >
> > > On Friday, December 9, 2016 1:59:44 PM CET sayan chaudhuri wrote:
> > > > Hi,
> > > >
> > > >    I am running QE self - consistently for my heusler alloy(Fe2TiSn)
> > > >
> > > > system, where 25% of Sn were replaced by Sb. But after 800 iterations
> > > > and
> > > > almost 3 hours of running also still it is not converged.
> > > > The code I am using is added bellow. Please tell me what is the
> source
> > > > of
> > > > error.
> > > >
> > > > Thanking you,
> > > >
> > > >    Sayan Chaudhuri
> > > >
> > > > *&control    prefix='fts',    calculation  = 'scf',    verbosity =
> > > > 'low',    pseudo_dir   = '/home/ltp/Desktop/espresso-5.4.0/pseudo',
> > > > outdir       = './tmp', / &system    ibrav=2    celldm(1)=11.43,
> > > > nat=16,    ntyp=4,        nspin=2,    ecutwfc=30.0,
> > > > starting_magnetization(1) =  0.0,    starting_magnetization(2) =
> 0.0,
> > > > starting_magnetization(3) =  0.5,    starting_magnetization(3) =
> 0.0,
> > > > occupations='tetrahedra',    / &electrons    electron_maxstep = 3000,
> > > > diagonalization = 'david',    mixing_mode = 'plain',    conv_thr =
> 1e-8,
> > > > mixing_beta=0.1, /ATOMIC_SPECIES  Sb   121.76   Sb.pz-bhs.UPF  Sn
> > > > 118.71   Sn.pz-dn-rrkjus_psl.0.2.UPF  Fe   55.845
>  Fe.pz-sp-van_ak.UPF
> > > > Ti   47.867   Ti.pz-sp-van.UPFATOMIC_POSITIONS {crystal} Sb
> > > > 0.000000000         0.000000000         0.000000000 Sn
> > > > 0.000000000         0.500000000         0.500000000 Sn
> > > > 0.500000000         0.000000000         0.500000000 Sb
> > > > 0.500000000         0.500000000         0.000000000 Fe
> > > > 0.250000000         0.250000000         0.250000000 Fe
> > > > 0.750000000         0.750000000         0.750000000 Fe
> > > > 0.750000000         0.750000000         0.250000000 Fe
> > > > 0.250000000         0.250000000         0.750000000 Fe
> > > > 0.750000000         0.250000000         0.750000000 Fe
> > > > 0.250000000         0.750000000         0.250000000 Fe
> > > > 0.250000000         0.750000000         0.750000000 Fe
> > > > 0.750000000         0.250000000         0.250000000 Ti
> > > > 0.500000000         0.500000000         0.500000000 Ti
> > > > 0.500000000         0.000000000         0.000000000 Ti
> > > > 0.000000000         0.500000000         0.000000000 Ti
> > > > 0.000000000         0.000000000         0.500000000 K_POINTS
> {automatic}
> > > > 2 2 2 0 0 0*
> > >
> > > --
> > > Dr. Lorenzo Paulatto
> > > IdR @ IMPMC -- CNRS & Université Paris 6
> > > phone: +33 (0)1 44275 084 / skype: paulatz
> > > www:   http://www-int.impmc.upmc.fr/~paulatto/
> > > mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris
> Cédex 05
> > >
> > > _______________________________________________
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>
>
> --
> Dr. Lorenzo Paulatto
> IdR @ IMPMC -- CNRS & Université Paris 6
> phone: +33 (0)1 44275 084 / skype: paulatz
> www:   http://www-int.impmc.upmc.fr/~paulatto/
> mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
>
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