[Pw_forum] Nd2Fe14B Magnetization
Arles V. Gil Rebaza
arvifis at gmail.com
Mon Jun 16 17:27:36 CEST 2014
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>:
>
>
> 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
>
>
>
>
>
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>
--
###---------> Arles V. <---------###
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