[Pw_forum] big difference between "total magnetization" and "absolute magnetization" for 4f elements

[Stefano de Gironcoli]

are you sure you are defining the correct magnetic structure ?
is Gd maybe antiferromagnetic ?
stefano

On 03/13/2013 03:19 PM, 琨陶 wrote:
> Dear everyone,
>
> I want to calculate the magnetic properties of bulk Gd whose magnetic
> moment is about 8 Bohr magneto/atom. Usually, in the output file
> values of "total magnetization" and "absolute magnetization" should be
> nearly the same. However, in my output file, I found a big difference
> between them as following:
>
>       total magnetization       =     8.00 Bohr mag/cell
>       absolute magnetization    =    15.72 Bohr mag/cell
>
> The good news is that the "absolute magnetization" is close to the
> experimental results (7.86 Bohr mag/atom), the bad news is that the
> "total magnetization" is wrong. Moreover, when I try to calculate the
> magnetic moment on each atom with projwfc.x program, I got about 4.1
> Bohr mag/atom.
>
> Could you give me some suggestions? Any advice are appreciated, thanks!
>
> Regards,
> Kun Tao
>
>
> Attached below is the input file:
>
>   &control
>      calculation='scf'
>      restart_mode='from_scratch',
>      prefix='Gd',
>      pseudo_dir = './'
>      outdir='./',
>   /
>   &system
>      ibrav= 4, celldm(1)= 6.96, celldm(3)= 1.59,
>      nat= 2, ntyp=1,
>      nspin = 2,
>      starting_magnetization(1)=1.0,
>      ecutwfc=55.0,
>      ecutrho=220.0,
>      occupations ='smearing',
>      smearing ='gauss',
>      degauss = 0.01,
>   /
>   &electrons
>      diagonalization='david',
>      mixing_beta = 0.3,
>      conv_thr = 1.0d-8,
>   /
> ATOMIC_SPECIES
>   Gd  1.0  Gd.GGA-PBE-paw.UPF
> ATOMIC_POSITIONS {crystal}
> Gd  0.33333333  0.66666667  0.25
> Gd  0.66666667  0.33333333  0.75
> K_POINTS {automatic}
> 4 4 4 0 0 0
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