[QE-users] Relax calculation of strontium hexaferrite using QE

[Lorenzo Paulatto]

Converging the self-consistent field with DFT+U can be difficult. To start, reduce mixing_beta (see manual), and also remove disk_io='high' unless you have a reason to use it. Also, your values of the U parameters seem to be arbitrary, if they are absurd it is very likely that SCF will never converge, try to relax without the +U to begin, then find a first approximation of U (by first principles or fitting some physical parameter) and relax again

--
Lorenzo Paulatto - Paris
On Feb 2 2021, at 10:54 am, Dr. SUNIL KUMAR <suniliitd14 at gmail.com> wrote:
> Dear Developers and users of QE.
> I am struggling to optimize the structure of strontium hexaferrite durin relax calculation of DFT using QE as given in the following script and attached snapshot. It is taking too much time and send some unexpected error as
>
> convergence NOT achieved after 100 iterations: stoppingv
> or
> convergence NOT achieved after 200 iterations: stopping
>
>
> Can anyone suggest me any modification in the following script.
> I will be too much grateful.
> Thanks
> With regards
> SUNIL
>
> &CONTROL
> calculation = "relax"
> prefix = "espresso"
> tprnfor = .TRUE.
> tstress = .TRUE.
> wf_collect = .TRUE.
> verbosity = 'high'
> disk_io = 'high'
> forc_conv_thr = 1.00000e-03
> nstep = 200
> pseudo_dir = "/home/pseudopot"
> outdir = "./outdir"
> wfcdir = "./wfcdir"
> /
>
> &SYSTEM
> a = 5.99774e+00
> c = 2.33482e+01
> degauss = 1.00000e-02
> ecutrho = 250
> ecutwfc = 25
> ibrav = 4
> nat = 64
> nspin = 2
> ntyp = 3
> occupations = "smearing"
> smearing = "gaussian"
> starting_magnetization(1) = 0.00000e+00
> starting_magnetization(2) = 0.2
> starting_magnetization(3) = 0.00000e+00
> lda_plus_u = .true.
> lda_plus_u_kind = 0
> Hubbard_U(2) = 4
> Hubbard_J(1,1) = 0
> Hubbard_J(2,2) = 1
>
> /
> &ELECTRONS
> conv_thr = 1.00000e-06
> electron_maxstep = 500
> mixing_beta = 4.00000e-01
> startingpot = "atomic"
> startingwfc = "atomic+random"
>
> /
> &IONS
> ion_dynamics = "bfgs"
> /
>
> &CELL
> /
>
>
> K_POINTS {automatic}
> 3 3 1 0 0 0
>
> ATOMIC_SPECIES
> Sr 87.62000 Sr.pbe-nsp-van.UPF
> Fe 55.84500 Fe.pbe-nd-rrkjus.UPF
> O 15.99940 O.pbe-rrkjus.UPF
>
> ATOMIC_POSITIONS {angstrom}
> Sr -0.000000 3.462796 17.511161
> Sr 2.998869 1.731398 5.837054
> Fe 0.000000 0.000000 0.000000
> Fe 0.000000 0.000000 11.674107
> Fe 0.000000 0.000000 17.511161
> Fe 0.000000 0.000000 5.837054
> Fe 2.998869 1.731398 22.706489
> Fe -0.000000 3.462796 0.641726
> Fe -0.000000 3.462796 11.032382
> Fe 2.998869 1.731398 12.315833
> Fe 2.998869 1.731398 18.887702
> Fe -0.000000 3.462796 4.460513
> Fe -0.000000 3.462796 7.213594
> Fe 2.998869 1.731398 16.134621
> Fe 2.998869 3.447345 2.560692
> Fe 1.512816 0.873424 2.560692
> Fe 4.484923 0.873424 2.560692
> Fe 0.000000 1.746849 20.787523
> Fe 1.486054 4.320769 20.787523
> Fe -1.486054 4.320769 20.787523
> Fe 0.000000 1.746849 14.234800
> Fe 1.486054 4.320769 14.234800
> Fe -1.486054 4.320769 14.234800
> Fe 2.998869 3.447345 9.113415
> Fe 1.512816 0.873424 9.113415
> Fe 4.484923 0.873424 9.113415
> O 0.000000 0.000000 19.782055
> O 0.000000 0.000000 3.566160
> O 0.000000 0.000000 8.107948
> O 0.000000 0.000000 15.240267
> O 2.998869 1.731398 1.300869
> O -0.000000 3.462796 22.047346
> O -0.000000 3.462796 12.974977
> O 2.998869 1.731398 10.373238
> O 2.998869 3.294521 17.511161
> O 1.645165 0.949836 17.511161
> O 4.352574 0.949836 17.511161
> O 0.000000 1.899672 5.837054
> O 1.353705 4.244357 5.837054
> O -1.353705 4.244357 5.837054
> O 2.998869 3.580534 22.111857
> O 1.397470 0.806830 22.111857
> O 4.600268 0.806830 22.111857
> O 0.000000 1.613659 1.236358
> O 1.601399 4.387364 1.236358
> O -1.601399 4.387364 1.236358
> O 0.000000 1.613659 10.437749
> O 1.601399 4.387364 10.437749
> O -1.601399 4.387364 10.437749
> O 2.998869 3.580534 12.910466
> O 1.397470 0.806830 12.910466
> O 4.600268 0.806830 12.910466
> O 0.000000 5.134086 19.813669
> O -1.447380 2.627150 19.813669
> O 1.447380 2.627150 19.813669
> O 2.998869 0.060107 3.534546
> O 4.446249 2.567043 3.534546
> O 1.551489 2.567043 3.534546
> O 2.998869 0.060107 8.139561
> O 4.446249 2.567043 8.139561
> O 1.551489 2.567043 8.139561
> O 0.000000 5.134086 15.208654
> O -1.447380 2.627150 15.208654
> O 1.447380 2.627150 15.208654
>
>
> Dr. Sunil Kumar
> Ph.D (Chemical Engg. IIT Delhi)
> M.Tech (Chemical Engg. IIT Delhi)
>
> B.Tech (Chemical Engg. IET-CSJMU Kanpur)
> Scientist-C and Assistant Professor
> CSIR-National Metallurgical Laboratory Jamshedpur-831007
> http://www.nmlindia.org/
>
> https://scholar.google.co.in/citations?user=OchYqugAAAAJ&hl=en&oi=sra
>
>
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20210204/5f745cf5/attachment.html>