[Pw_forum] Nd2Fe14B Magnetization
Pang Rui
pang.r at sustc.edu.cn
Tue Jun 17 13:50:18 CEST 2014
Maybe you can check if different starting magnetizations converge into
one.
On Tue, 17 Jun 2014 02:02:41 +0000, "Kurth, Michael R."
<kurth.17 at buckeyemail.osu.edu> wrote:
> Dear Juanjo,
>
> Thank you for the advice. We did try a DFT+U calculation only on the
> neodymium atoms, but it was also with the default number of bands. We
saw
> similar results in terms of total magnetization as the other
calculations
> we ran without the +U correction.
>
> Thanks,
> Michael
>
> Graduate Student in Nuclear Engineering
> Department of Mechanical and Aerospace Engineering
> The Ohio State University
>
>
> From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On
> Behalf Of Juanjo Meléndez
> Sent: Monday, June 16, 2014 1:37 PM
> To: PWSCF Forum
> Subject: Re: [Pw_forum] Nd2Fe14B Magnetization
>
> Dear Michael
>
> I think that the problem is the presence of Nd in your lattice. As far
as
> I know, f-electrons are not only tricky to handle within a DFT
formalism,
> but they constitute the border of its validity. I would not expect a
great
> degree of accuracy in your calculations for any PP you may use.
>
> Anyway, you could try with DFT+U with the proper correction for
correlated
> f-electrons (and maybe d-electrons from Fe as well). Sometimes it is
hard
> to converge, but it could help. Anyway, I would not expect any miracle.
>
> BTW. Do not waste your time trying to change ecutrho. You are using a
> norm-conserving pseudopotential, so that ecutrho is meaningless.
>
> Good luck
>
> Juanjo
>
> Juan J. Meléndez
> Associate Professor
> Department of Physics · University of Extremadura
> Avda. de Elvas, s/n 06006 Badajoz (Spain)
> Phone: +34 924 28 96 55
> Fax: +34 924 28 96 51
> Email: melendez at unex.es
> Web: http://materiales.unex.es/miembros/personal/jj-melendez/Index.html
>
> From: Kurth, Michael R.<mailto:kurth.17 at buckeyemail.osu.edu>
> Sent: Monday, June 16, 2014 5:52 PM
> To: PWSCF Forum<mailto:pw_forum at pwscf.org>
> Subject: Re: [Pw_forum] Nd2Fe14B Magnetization
>
> Dear Dr. Rebaza,
>
> Thank you for the reply. We did increase ecutrho to approximately 6
times
> the ecutwfc value and did not see a notable difference in the
calculation.
> As far as the value of ecutwfc=260, we arrived at this value after
running
> calculations at ecutwfc=300 and not observing a 1 mRy/atom difference in
> the total energy. We also have tested PBE and PW pseudopotentials but
have
> not observed a difference in the total magnetization value.
>
> Sincerely,
> Michael Kurth
>
> Graduate Student in Nuclear Engineering
> Department of Mechanical and Aerospace Engineering
> The Ohio State University
> From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On
> Behalf Of Arles V. Gil Rebaza
> Sent: Monday, June 16, 2014 11:28 AM
> To: PWSCF Forum
> Subject: Re: [Pw_forum] Nd2Fe14B Magnetization
>
> Dear Michael, are you sure that "ecutwfc = 260.0" is a enough value for
> your system, may be you should increse, and you're using the default
value
> of "ecutrho", try to converge with this tag.!!!
>
> Best
>
> PhD. Arles V. GIl Rebaza
> Instituto de Física La Plata
> La Plata - Argentina
>
> 2014-06-16 12:16 GMT-03:00 Kurth, Michael R.
> <kurth.17 at buckeyemail.osu.edu<mailto:kurth.17 at buckeyemail.osu.edu>>:
>
>
> Hello,
>
>
>
> I am trying to calculate the magnetization of NdFeB which is a
> ferromagnetic material and a metal. This calculation has been done
before
> using different methods than plane waves and pseudopotentials. Moreover,
> the magnetization per formula unit has been experimentally measured. The
> previous calculations and experimental values agree and report a
> magnetization per formula unit of around 37 Bohr Magneton. The previous
> calculations used the Generalized Gradient Approximation for the
exchange
> correlation functional.
>
>
>
> We first tried the calculation using the default number of bands and the
> input file is attached below:
>
>
>
> &control
>
> calculation='scf'
>
> restart_mode='from_scratch',
>
> wf_collect=.TRUE.,
>
> prefix='NdFeB',
>
> pseudo_dir = '/usr/local/espresso/espresso-5.0.3/pseudo/',
>
> outdir = '/fs/lustre/osu7834/NdFeB/'
>
> /
>
> &system
>
> ibrav=0, nat=68, ntyp=3,
>
> nspin=2, starting_magnetization(1)=0.6,
starting_magnetization(2)=0.6,
> starting_magnetization(3)=0.6,
>
> ecutwfc = 260.0
>
> occupations='smearing', smearing='mv', degauss=0.002
>
> /
>
> &electrons
>
> conv_thr=1.0e-6
>
> mixing_beta=0.02
>
> mixing_mode = 'local-TF'
>
> /
>
> CELL_PARAMETERS {angstrom}
>
> 8.8 0.0 0.0
>
> 0.0 12.19 0.0
>
> 0.0 0.0 8.8
>
> ATOMIC_SPECIES
>
> Nd 144.24 Nd.pbe-mt_fhi.UPF
>
> Fe 55.845 Fe.pbe-mt_fhi.UPF
>
> B 10.811 B.pbe-mt_fhi.UPF
>
> ATOMIC_POSITIONS {angstrom}
>
> B 5.54400 0.00000 3.25600
>
> B 3.25600 0.00000 5.54400
>
> B 7.65600 6.09500 7.65600
>
> B 1.14400 6.09500 1.14400
>
> Fe 4.40000 0.00000 0.00000
>
> Fe 4.40000 6.09500 0.00000
>
> Fe 0.00000 6.09500 4.40000
>
> Fe 0.00000 0.00000 4.40000
>
> Fe 4.40000 1.37747 4.40000
>
> Fe 0.00000 7.47247 0.00000
>
> Fe 0.00000 4.71753 0.00000
>
> Fe 4.40000 10.81253 4.40000
>
> Fe 0.85360 2.49895 0.85360
>
> Fe 7.94640 2.49895 7.94640
>
> Fe 5.25360 8.59395 3.54640
>
> Fe 3.54640 8.59395 5.25360
>
> Fe 5.25360 3.59605 3.54640
>
> Fe 3.54640 3.59605 5.25360
>
> Fe 0.85360 9.69105 0.85360
>
> Fe 7.94640 9.69105 7.94640
>
> Fe 2.79840 3.01093 2.79840
>
> Fe 6.00160 3.01093 6.00160
>
> Fe 7.19840 9.10593 1.60160
>
> Fe 1.60160 9.10593 7.19840
>
> Fe 7.19840 3.08407 1.60160
>
> Fe 1.60160 3.08407 7.19840
>
> Fe 2.79840 9.17907 2.79840
>
> Fe 6.00160 9.17907 6.00160
>
> Fe 4.99840 1.56032 1.97120
>
> Fe 3.80160 1.56032 6.82880
>
> Fe 6.37120 7.65532 8.20160
>
> Fe 2.42880 7.65532 0.59840
>
> Fe 0.59840 4.53468 2.42880
>
> Fe 8.20160 4.53468 6.37120
>
> Fe 1.97120 10.62968 4.99840
>
> Fe 6.82880 1.56032 3.80160
>
> Fe 3.80160 10.62968 6.82880
>
> Fe 4.99840 10.62968 1.97120
>
> Fe 2.42880 4.53468 0.59840
>
> Fe 6.37120 4.53468 8.20160
>
> Fe 8.20160 7.65532 6.37120
>
> Fe 0.59840 7.65532 2.42880
>
> Fe 6.82880 10.62968 3.80160
>
> Fe 1.97120 1.56032 4.99840
>
> Fe 3.15920 2.14544 0.34320
>
> Fe 5.64080 2.14544 8.45680
>
> Fe 4.74320 8.24044 1.24080
>
> Fe 4.05680 8.24044 7.55920
>
> Fe 7.55920 3.94956 4.05680
>
> Fe 1.24080 3.94956 4.74320
>
> Fe 0.34320 10.04456 3.15920
>
> Fe 8.45680 2.14544 5.64080
>
> Fe 5.64080 10.04456 8.45680
>
> Fe 3.15920 10.04456 0.34320
>
> Fe 4.05680 3.94956 7.55920
>
> Fe 4.74320 3.94956 1.24080
>
> Fe 1.24080 8.24044 4.74320
>
> Fe 7.55920 8.24044 4.05680
>
> Fe 8.45680 10.04456 5.64080
>
> Fe 0.34320 2.14544 3.15920
>
> Nd 2.34080 0.00000 2.34080
>
> Nd 6.45920 0.00000 6.45920
>
> Nd 6.74080 6.09500 2.05920
>
> Nd 2.05920 6.09500 6.74080
>
> Nd 7.56800 0.00000 1.23200
>
> Nd 1.23200 0.00000 7.56800
>
> Nd 5.63200 6.09500 5.63200
>
> Nd 3.16800 6.09500 3.16800
>
>
>
> K_POINTS {automatic}
>
> 4 4 4 0 0 0
>
>
>
>
>
> This input file was prepared after checking convergence with respect to
> the energy cutoff and the number of points and did converge after 2
restart
> runs. Unfortunately, we obtained a magnetization of 25 Bohr
Magneton/f.u.
> (which is too small).
>
>
>
> Furthermore, and after checking for convergence with respect to the
number
> of bands (by adding more bands) we found that we end up with a
> magnetization of 50 Bohr Magneton/f.u. (which is too big).
>
> I also think that the degauss value used for smearing is small enough
and
> can't be the problem.
>
> Are there any recommendations for what other parameters I could examine
to
> help me get the right answer?
>
>
>
> Your help is greatly appreciated!
>
>
>
> Sincerely,
> Michael Kurth
>
>
> Graduate Student in Nuclear Engineering
>
> Department of Mechanical and Aerospace Engineering
>
> The Ohio State University
>
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org<mailto:Pw_forum at pwscf.org>
> http://pwscf.org/mailman/listinfo/pw_forum
>
>
>
> --
> ###---------> Arles V. <---------###
> ________________________________
> No virus found in this message.
> Checked by AVG - www.avg.com<http://www.avg.com>
> Version: 2014.0.4592 / Virus Database: 3964/7686 - Release Date:
06/16/14
> ________________________________
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
> ________________________________
> [Image removed by sender.]<http://www.avast.com/>
>
>
> Este mensaje no contiene virus ni malware porque la protección de avast!
> Antivirus<http://www.avast.com/> está activa.
>
>
> ________________________________
> No virus found in this message.
> Checked by AVG - www.avg.com<http://www.avg.com>
> Version: 2014.0.4592 / Virus Database: 3964/7686 - Release Date:
06/16/14
--
PostDoc
Department of Physics, South University of Science and Technology of China
More information about the users
mailing list