[Pw_forum] Wrong occupation number for f electrons

[琨陶]

Dear everyone,

I want to calculate the magnetic properties of bulk Gd which contains two
Gd atoms in the unit cell. In the input files, I set two Gd atoms to be
ferromagnetic configuration. I searched the occupation number for each atom
In the output file, and found following information:

At the beginning:

atom    1   Tr[ns(na)] (up, down, total) =   7.00000  0.00000  7.00000
atom    2   Tr[ns(na)] (up, down, total) =   7.00000  0.00000  7.00000

However, after the first iteration, I found the occupation number of the
first atom is totally wrong as following:

atom    1   Tr[ns(na)] (up, down, total) =   7.00064  5.60439 12.60503
atom    2   Tr[ns(na)] (up, down, total) =   6.87289  0.00836  6.88125

At the last iteration, I found:

atom    1   Tr[ns(na)] (up, down, total) =   3.60781  3.88818  7.49599
atom    2   Tr[ns(na)] (up, down, total) =   7.00165  0.09767  7.09932

But, when I changed these two Gd atoms to be antiferromagnetic case, both
of them had correct occupation number as fellowing:

atom    1   Tr[ns(na)] (up, down, total) =   7.00000  0.00000  7.00000
atom    2   Tr[ns(na)] (up, down, total) =   0.00000  7.00000  7.00000
atom    1   Tr[ns(na)] (up, down, total) =   7.00291  0.02028  7.02319
atom    2   Tr[ns(na)] (up, down, total) =   0.00924  7.00258  7.01182
atom    1   Tr[ns(na)] (up, down, total) =   7.00130  0.12233  7.12362
atom    2   Tr[ns(na)] (up, down, total) =   0.11939  7.00128  7.12068

Could you give me some suggestions? Any advices are highly appreciated!

With regards,
Kun Tao


PS: The following 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=2,
    nspin = 2,
    starting_magnetization(1)=1.0,
    starting_magnetization(2)=1.0,

    ecutwfc=55.0,
    ecutrho=220.0,
    occupations ='smearing',
    smearing ='gauss',
    degauss = 0.01,
    lda_plus_u = .true.
    Hubbard_U(1)= 1.d-20
    Hubbard_U(2)= 1.d-20

 /
 &electrons
    diagonalization='david',
    mixing_beta = 0.3,
    conv_thr = 1.0d-6,
    electron_maxstep = 400,
 /
ATOMIC_SPECIES
 Gd1  1.0  Gd.GGA-PBE-paw.UPF

 Gd   1.0  Gd.GGA-PBE-paw.UPF
ATOMIC_POSITIONS {crystal}
Gd1  0.00000000  0.00000000  0.00
Gd   0.33333333 -0.33333333  0.50
K_POINTS {automatic}
2 2 2 0 0 0
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