[Pw_forum] SCF run not converging

[Lorenzo Paulatto]

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
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> *&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