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

[琨陶]

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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