[QE-users] Fe (110) slab isn't converging

[Thomas Brumme]

Dear Omer,

what is not converging? The scf or the relaxation?
Looking at your input I can see one main problem: the cutoff. Please 
have a look at this very useful page:

https://www.materialscloud.org/discover/sssp/plot/efficiency/Fe

The pseudopotential you're using needs much more than 30 Ry cutoff. I 
guess that you will need to increase the cutoff to at least 50 Ry for 
the wave functions and 400 Ry for the density.
Furthermore, your smearing is quite low. If you have problems with 
convergence, increasing this to ~100meV can help.

Kind regards

Thomas

On 2/10/22 11:41, Omer Mutasim via users wrote:
> Dear all
> I tried to relax Fe (110) slab , but it doesn't converge. It takes 
> very long time even though it is small slab with only 45 atoms.
>  I tried f-d, m-p smearing but to no avail.
> Can you help me please ? to know what is wrong with my input file 
> attached below:
>
> &CONTROL
>     calculation   = "relax"
> prefix = 'x'
>     outdir = '/scratch'
>     pseudo_dir = '/xx/'
> !restart_mode = 'restart'
>     forc_conv_thr =  1.0e-03
> etot_conv_thr=1e-04
>     nstep         = 9999
>
> /
>
> &SYSTEM
> ibrav  =0
>     ecutrho   = 150
>     ecutwfc   = 30
>     nat       = 45
>     ntyp      = 1
> occupations ='smearing' , smearing='f-d' , degauss=0.005
> vdw_corr    = 'DFT-D3'
> nspin = 2
> starting_magnetization(1) = 0.1
> /
> &ELECTRONS
>     conv_thr         =1e-06
>     electron_maxstep = 9999
> mixing_mode='local-TF'
>     mixing_beta      =  0.3
> /
>
> &IONS
> /
>
> K_POINTS {automatic}
> 221000
>
> ATOMIC_SPECIES
> Fe  55.845   Fe.pbe-spn-kjpaw_psl.0.2.1.UPF
> CELL_PARAMETERS {angstrom}
>         7.4474000931         0.0000000000  0.0000000000
>         2.4824640508         7.0214770799  0.0000000000
>         0.0000000000         0.0000000000 25.1350002289
> ATOMIC_POSITIONS (angstrom)
> Fe            5.5818789877        2.5026591675  10.5421792561    0   0   0
> Fe            4.1125866520        4.8151882619  10.6772393880
> Fe            2.1958530690        7.2414707420  10.3206255931
> Fe            1.1033564060        1.9504258780 0.0000000000    0   0   0
> Fe            1.1240846033        1.9239546627 4.4015746387
> Fe            0.5929191720        2.2727761723 9.2300878464    0   0   0
> Fe            1.9418633362        0.7673280599 2.1503683749
> Fe            1.8505911190        0.7816285240 6.8697562640
> Fe            3.5857982640        1.9504258780 0.0000000000    0   0   0
> Fe            3.6010156782        2.0356057803 4.4040536951
> Fe            3.3892107507        2.4333408596 9.2315052153    0   0   0
> Fe            4.4107991582        0.7671459373 2.2844419078
> Fe            4.3403612910        0.9089118831 6.8687340519
> Fe            6.0682401770        1.9504258780 0.0000000000    0   0   0
> Fe            6.0921186925        1.9492701251 4.5081309218
> Fe            6.8957462620        0.7801563310 2.0268864960    0   0   0
> Fe            6.8261914569        0.9046029160 6.7661838994
> Fe            1.8724868770        4.4014805858  -0.2143812725
> Fe            1.8485507821        4.2994702275 4.3824953904    0   0   0
> Fe            1.8240284641        4.7344494204 9.2345798280
> Fe            2.7582676160        3.1206253240 2.0268864960    0   0   0
> Fe            2.6683169740        3.1739888190 6.8797363658
> Fe            4.3474449433        4.3631009861  -0.1911888976
> Fe            4.3246850209        4.4213381253 4.3668090656    0   0   0
> Fe            5.2753804683        3.1017230426 2.1588431075
> Fe            5.1435681580        3.2467521647 6.6302721725    0   0   0
> Fe            6.8866553226        4.2727158920  -0.2151129276
> Fe            6.8148177194        4.3601995734 4.3973105493
> Fe            6.4979897094        4.6088015071 9.2447583930    0   0   0
> Fe            7.7586179448        3.1003648378 2.1698200674
> Fe            7.6317422302        3.2430726605 6.8687193850    0   0   0
> Fe            2.7205563083        6.7460510219  -0.2000658247
> Fe            2.7608454757        6.6172987829 4.5215696688
> Fe            3.5857721560        5.4611644180 2.0268864960    0   0   0
> Fe            3.6115378719        5.4595736549 6.6122865627
> Fe            5.2407577750        6.6313638640 0.0000000000    0   0   0
> Fe            5.2548206739        6.7098271636 4.3861096452
> Fe            4.8691076063        6.9050837980 9.2329583714
> Fe            6.0682884220        5.4611644180 2.0268864960    0   0   0
> Fe            6.1028694761        5.5498338413 6.8798135598
> Fe            7.7231996880        6.6313638640 0.0000000000    0   0   0
> Fe            7.7426438544        6.6251084192 4.3864901090
> Fe            7.3977446239        6.9684054207 9.2402605725
> Fe            8.5507305580        5.4611644180 2.0268864960    0   0   0
> Fe            8.6014581434        5.5444835700 6.8763383415
>
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-- 
Dr. rer. nat. Thomas Brumme
Theoretical chemistry
TU Dresden - KOE / 103
Bergstr. 66c
01069 Dresden

Tel:  +49 (0)351 463 40844

email:thomas.brumme at tu-dresden.de
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