[QE-users] convergence issue in DFT_U+V calculation

Matteo Cococcioni matteo.cococcioni at unipv.it
Wed Dec 1 12:24:03 CET 2021


Dear Bhamu,

you better use two different kinds for the Fe in octahedral sites: one for
2+ the other for 3+. they are likely to have different U's as well.

Matteo


Il giorno mer 1 dic 2021 alle ore 11:34 Dr. K. C. Bhamu <kcbhamu85 at gmail.com>
ha scritto:

> Dear Dr. Matteo,
>
> Thank you very much for the quick response.
>
> Yes, I am doing vc-relax in between each step.  Doing vc-relax without
> adopting geometry information from the previous run. I am only supplying
> the HP file containing U+V obtained from the previous run for the vc-relax
> for the next step.
>
> Fe1 (octahedral coordination) atom has a mixed charge state (Fe3+ and
> Fe2+).
> The magnetic moment of Fe1( Fe3+) cancels out with Fe2 (tetrahedral
> coordination; all Fe3+) and the resultant magnetic moment comes from Fe1
> (2+) atoms.
> According to Ref. [1]
> <https://www.sciencedirect.com/science/article/abs/pii/S0039602812000544>,
> I set all Fe1 as up and all Fe2 as down spins.
>
> Do you think my input still has some issues?
>
> -------------------
> I am providing some additional information here.
>
> Additional information:
>
> Ref. [1]
> <https://www.sciencedirect.com/science/article/abs/pii/S0039602812000544>
> Just below Fig. 3 it is mentioned that "For Fe3O4 having ferrimagnetic
> property, the spin of the octahedral and tetrahedral Fe was set as up and
> down, respectively."
>
>
> Relevant para from Ref. [2]
> <https://link.springer.com/article/10.1134%2FS1027451010030079> is as
> below:
> Fe2+ cations in the face-centered cubic lattice formed by oxygen anions
> occupy octahedral sites, while Fe3+ cations are distributed between
> octahedral and tetrahedral sites. The trivalent Fe3+ ion is in the state
> with a spin S = 5/2 and zero orbital moments. The bivalent Fe2+ ion has a
> spin of 2, and its contribution comes to ~4μB unless one considers a
> certain possible contribution from the orbital moment [2]. The measured
> value of the magnetic moment for magnetite is 4.1μB. The magnetic moments
> of Fe3+ ions are antiparallel to each other, and the observed moment is
> determined by Fe2+ ions only (Fig. 1).
>
>
> Thanks and regards
> Bhamu
>
>
>
> On Wed, Dec 1, 2021 at 2:17 PM Matteo Cococcioni <
> matteo.cococcioni at unipv.it> wrote:
>
>> the fourth iteration does not look too good to me as the U for Fe2 is
>> suddenly going from 4.31 to 0.7.
>> Fe3O4 is a difficult system of its own. are you sure that all the Fe1 are
>> of the same kind (3+)? The system is for sure
>> a mixed valence one but I don't remember how this matches its magnetic
>> structure. Are you relaxing the structure in between?
>> Maybe because of the structure changes hp is not recognizing the
>> neighbors it had before for each Fe.
>>
>> Regards,
>>
>> Matteo
>>
>> Il giorno mer 1 dic 2021 alle ore 06:07 Dr. K. C. Bhamu <
>> kcbhamu85 at gmail.com> ha scritto:
>>
>>> Dear Iurii,
>>> This is from the calculation without nbnd in QE input file (QE input and
>>> HP input are supplied at the end of this email).
>>> I am trying to get a converged value of U+V. Up to four steps, all the
>>> calculations seem to be fine (other than the converged value of U+V). But
>>> in the 5th step, I see that my calculations are not converging.
>>>
>>> I am getting this message:
>>>       atom #  5   q point #   3   iter # 180
>>>       chi:   1 -83.8242814567   residue:  103.6191835332
>>>       chi:   2 -83.8242814548   residue:  103.6191835384
>>>       chi:   3 **************   residue:  381.0626501229
>>>       chi:   4 **************   residue:  326.7198566114
>>>       chi:   5 317.5473216386   residue:  329.6382092529
>>>       chi:   6 **************   residue:  580.5784405595
>>>       chi:   7   9.0496504843   residue:    1.9763844786
>>>       chi:   8  -6.2884312048   residue:   21.8495062869
>>>       chi:   9   9.0496505082   residue:    1.9763845088
>>>       chi:  10  -6.2884312084   residue:   21.8495062832
>>>       chi:  11  10.2338160751   residue:    7.3557134894
>>>       chi:  12  -5.1687829951   residue:   22.9825921172
>>>       chi:  13   6.7503553298   residue:    7.1360232476
>>>       chi:  14  -3.9982889995   residue:   27.0388948104
>>>       Average number of iter. to solve lin. system:   23.6
>>>       Total CPU time : 63284.6 s
>>> ###################
>>>       atom #  5   q point #   3   iter # 274
>>>       chi:   1 **************   residue:  **************
>>>       chi:   2 **************   residue:  **************
>>>       chi:   3 **************   residue:  **************
>>>       chi:   4 **************   residue:  **************
>>>       chi:   5 **************   residue:  **************
>>>       chi:   6 **************   residue:  **************
>>>       chi:   7 **************   residue:   78.8265104616
>>>       chi:   8 190.5140692168   residue:  **************
>>>       chi:   9 **************   residue:   78.8264974402
>>>       chi:  10 190.5140679621   residue:  **************
>>>       chi:  11 **************   residue:  **************
>>>       chi:  12 544.1915326984   residue:  **************
>>>       chi:  13 **************   residue:  **************
>>>       chi:  14 **************   residue:  **************
>>>
>>> U+V value from four completed calculations is given below:
>>>
>>>
>>> site n.  type  label  spin  new_type  new_label  Hubbard U (eV)
>>>   1        1    Fe1     1      1         Fe1        5.1791
>>>   5        2    Fe2    -1      2         Fe2        5.0962
>>>   7        3    O       0      3         O          7.1203
>>>
>>> site n.  type  label  spin  new_type  new_label  Hubbard U (eV)
>>>   1        1    Fe1     1      1         Fe1        5.6013
>>>   5        2    Fe2    -1      2         Fe2        4.3164
>>>   7        3    O       0      3         O          7.5401
>>>
>>> site n.  type  label  spin  new_type  new_label  Hubbard U (eV)
>>>   1        1    Fe1     1      1         Fe1        5.6013
>>>   5        2    Fe2    -1      2         Fe2        4.3164
>>>   7        3    O       0      3         O          7.5401
>>>
>>> site n.  type  label  spin  new_type  new_label  Hubbard U (eV)
>>>   1        1    Fe1     1      1         Fe1        4.4843
>>>   5        2    Fe2    -1      2         Fe2        0.7259
>>>   7        3    O       0      3         O          7.3480
>>>
>>>
>>> I do not think changing "conv_thr_chi" will help here as the number is
>>> still oscillating in integer values.
>>>
>>> What suggestions do you have for this situation?
>>>
>>>
>>> HP input file:
>>>
>>>  &inputhp
>>>    prefix = 'pwscf',
>>> niter_max=300
>>>    outdir = './temp/',
>>>    nq1 = 2, nq2 = 2, nq3 = 2,
>>>    conv_thr_chi = 1.0d-5,
>>> find_atpert = 1
>>> docc_thr=1.d-3
>>> !disable_type_analysis=.true.,
>>> /
>>>
>>> QE input file:
>>> &CONTROL
>>>   calculation = 'vc-relax'
>>>   restart_mode='from_scratch',
>>>   etot_conv_thr =   1.4000000000d-04
>>>   forc_conv_thr =   1.0000000000d-04
>>>   outdir = './temp/'
>>>   prefix = 'pwscf'
>>>   pseudo_dir = '~/PPs/jana_2/'
>>>   tprnfor = .true.
>>>   tstress = .true.
>>>   verbosity = 'high'
>>> /
>>> &SYSTEM
>>>   degauss =   0.022
>>>   ecutrho =   320
>>>   ecutwfc =   40
>>>   occupations = 'smearing' ,    smearing = 'mp'
>>>   ibrav = 0
>>>   nat = 14
>>>   nosym = .false.
>>>   ntyp = 3
>>> nspin=2
>>>   starting_magnetization(1) =   0.8
>>>   starting_magnetization(2) =   -0.8
>>>   starting_magnetization(3) =   0.0
>>>
>>>   lda_plus_u = .true.,
>>>   lda_plus_u_kind = 2,
>>>   U_projection_type = 'ortho-atomic',
>>>   !Hubbard_V(1,1,1) = 1.d-8
>>>   !Hubbard_V(5,5,1) = 1.d-8
>>>   !Hubbard_V(7,7,1) = 1.d-8
>>> Hubbard_parameters = 'file'
>>>
>>>
>>> /
>>> &ELECTRONS
>>>   conv_thr =   1.0000000000d-06
>>>   electron_maxstep = 400
>>>   mixing_beta =   1.5000000000d-01
>>> /
>>> &IONS
>>>                 ion_dynamics = 'bfgs'
>>>  /
>>> &CELL
>>> /
>>>
>>> ATOMIC_SPECIES
>>> Fe1     55.845 Fe.pbe-nd-rrkjus.UPF
>>> Fe2     55.845 Fe.pbe-nd-rrkjus.UPF
>>> O      15.9994 O.pbe-rrkjus.UPF
>>> ATOMIC_POSITIONS (crystal)
>>> Fe1           0.0000000000       -0.0000000000       -0.0000000000
>>> Fe1           0.5000000000        0.0000000000        0.0000000000
>>> Fe1           0.9999999892        0.5000000216       -0.0000000000
>>> Fe1           0.9999999965        0.9999999956        0.5000000115
>>> Fe2           0.3749993721        0.3749993349        0.3750019210
>>> Fe2           0.6250006225        0.6250006532        0.6249981020
>>> O             0.2454868415        0.2454868399        0.2454949640
>>> O             0.7545131845        0.7545131098        0.7545050345
>>> O             0.7635313546        0.2454868399        0.2454949640
>>> O             0.2364686713        0.7545131098        0.7545050345
>>> O             0.2454868307        0.7635313746        0.2454949640
>>> O             0.7545132523        0.2364686217        0.7545050345
>>> O             0.2454908593        0.2454908222        0.7635274591
>>> O             0.7545090629        0.7545091741        0.2364725394
>>>
>>> CELL_PARAMETERS (angstrom)
>>>    5.944682649   0.000000000   0.000000000
>>>    2.972341325   5.148246192   0.000000000
>>>    2.972341325   1.716082064   4.853885701
>>>
>>> K_POINTS automatic
>>> 7 7 7 0 0 0
>>>
>>>
>>> Regards
>>> Bhamu
>>>
>>> _______________________________________________
>>> 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
>>
>>
>>
>> --
>> Matteo Cococcioni
>> Department of Physics
>> University of Pavia
>> Via Bassi 6, I-27100 Pavia, Italy
>> tel +39-0382-987485
>> e-mail matteo.cococcioni at unipv.it <lucio.andreani at unipv.it>
>> _______________________________________________
>> 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
>
> _______________________________________________
> 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



-- 
Matteo Cococcioni
Department of Physics
University of Pavia
Via Bassi 6, I-27100 Pavia, Italy
tel +39-0382-987485
e-mail matteo.cococcioni at unipv.it <lucio.andreani at unipv.it>
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