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

[Andrei Malashevich]

If you want to model antiferromagnetic structure, you should define two
types of atoms, Gd1 and Gd2.
Change ntyp to 2. Use, e.g.,
 starting_magnetization(1)=1.0
starting_magnetization(2)=-1.0

ATOMIC_SPECIES
 Gd1  1.0  Gd.GGA-PBE-paw.UPF
 Gd2  1.0  Gd.GGA-PBE-paw.UPF
ATOMIC_POSITIONS {crystal}
Gd1  0.33333333  0.66666667  0.25
Gd2 0.66666667  0.33333333  0.75


On Wed, Mar 13, 2013 at 11:05 AM, 琨陶 <taokun76 at gmail.com> wrote:

> Hi,
>
> Yes, the bulk Gd without Hubbard U is antiferromagnetic. If I set the
> two atoms in the unit cell to be antiferromagnetic, the "total
> magnetization" should be equal to zero, and the "absolute
> magnetization" is what I have gotten. Now, however, the "total
> magnetization" is not zero. Could you give me some suggestions?
> Thanks!
>
> With regards,
> Kun Tao
>
> On 13 March 2013 10:48, Stefano de Gironcoli <degironc at sissa.it> wrote:
> > 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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> >
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