hyperfine coupling constant

[mouna]

I'm trying to calculate the fermi contact and the hyperfine coupling constant using the 5.3.5 and the new potcar. The tables in the OUTCAR file show zero values...
--------------------------------------
My INCAR
PREC = Accurate
ENCUT = 700
NELMDL = -12
NELMIN= 5
ISYM = 0
LORBIT = 11
ISPIN=2

Ionic minimisation
ISIF = 3
EDIFFG = -1E-4
IBRION = 2
NSW = 100

ALGO = Fast
NELM = 210
ISMEAR = -5
NPAR = 4
# LREAL = Auto
LWAVE = .TRUE.
LCHARG = .TRUE.
LPLANE = .FALSE.

# LAECHG=.TRUE.

NGYROMAG = 11.268 10.189
LHYPERFINE =.TRUE.
#LEFG=.TRUE.
---------------------------------
Results
------------------------------------

Fermi contact (isotropic) hyperfine coupling parameter (MHz)
-------------------------------------------------------------
ion A_pw A_1PS A_1AE A_1c A_tot
-------------------------------------------------------------
1 0.000 -0.000 -0.000 -0.000 -0.000
2 -0.000 0.000 0.000 -0.000 0.000
3 -0.000 0.000 0.000 -0.000 0.000
4 -0.000 -0.000 0.000 -0.000 0.000
5 0.000 -0.000 -0.000 0.000 -0.000
6 0.000 -0.000 -0.000 0.000 -0.000
7 -0.000 -0.000 -0.000 0.000 -0.000
8 -0.000 -0.000 -0.000 0.000 -0.000
9 0.000 -0.000 -0.000 0.000 -0.000
10 -0.000 -0.000 -0.000 0.000 -0.000
11 -0.000 -0.000 -0.000 0.000 -0.000
12 -0.000 -0.000 -0.000 0.000 -0.000
13 0.000 0.000 -0.001 -0.000 -0.001
14 0.000 0.000 -0.001 -0.000 -0.001
15 0.000 0.000 -0.001 0.000 -0.001
16 0.000 0.000 -0.001 -0.000 -0.001
-------------------------------------------------------------


Dipolar hyperfine coupling parameters (MHz)
---------------------------------------------------------------------
ion A_xx A_yy A_zz A_xy A_xz A_yz
---------------------------------------------------------------------
1 0.000 -0.000 0.000 0.000 0.000 0.000
2 0.000 -0.000 0.000 0.000 -0.000 0.000
3 -0.000 -0.000 0.000 -0.000 0.000 -0.000
4 -0.000 -0.000 0.000 0.000 -0.000 -0.000
5 0.000 -0.000 0.000 -0.000 0.000 0.000
6 0.000 -0.000 -0.000 0.000 0.000 -0.000
7 0.000 -0.000 -0.000 -0.000 -0.000 0.000
8 0.000 0.000 -0.000 -0.000 0.000 0.000
9 -0.000 0.000 -0.000 -0.000 0.000 0.000
10 0.000 -0.000 0.000 0.000 0.000 0.000
11 0.000 0.000 -0.000 -0.000 0.000 -0.000
12 0.000 -0.000 -0.000 -0.000 -0.000 -0.000
13 0.000 0.000 -0.000 0.000 0.000 0.000
14 0.000 0.000 -0.000 -0.000 -0.000 -0.000
15 0.000 0.000 -0.000 0.000 -0.000 0.000
16 0.000 0.000 -0.000 0.000 -0.000 0.000
---------------------------------------------------------------------

Can anyone help me to fix the problem?
Thanks

[hongyang_ma]

Hi Mouna,

I have the same problem as yours. I'm wondering could you please share me some experience in how to solve this issue?

Thanks & Regards,
Hongyang

[hongyang_ma]

Dear Vasp users,

I'm currently using 'LHYPERFINE' to calculate the hyperfine constant of the shallow doping, but the results in OUTCAR show zero values in all the atoms. I'm wondering could someone who have done hyperfine constant calculation or have used LHYPERFINE share their experience to me? Thanks.

INCAR:
ISTART = 1
PREC = Normal
NCORE = 24
ISPIN = 2
ISMEAR = 0
SIGMA = 0.1
NELM = 100
EDIFF = 1E-06
NSW = 100
IBRION = 2
ISIF = 2
ENCUT = 450
EDIFFG = -1.5E-02
LHYPERFINE = .TRUE.
NGYROMAG = 17.235 -8.465 (There are 1 P, the first atom in POSCAR, and 200 Si in my structure, I'm not sure if this tag is written correctly.)

OUTCAR:

1.jpg

2.jpg

3.jpg

Thanks & Regards,
Hongyang

[martin.schlipf]

Can you please send a complete set of input files (INCAR, KPOINTS, POTCAR, POSCAR) and tell me which version of Vasp you are using?

[hongyang_ma]

Dear Martin,

The input files are attached. I'm using VASP-6.1.0.

Thanks & Regards,
Hongyang

[martin.schlipf]

I reproduced the behavior, i.e., the hyperfine coupling disappears. However your system relaxes towards a nonmagnetic solution so the disappearance of the hyperfine splitting is expected. If you believe your system should be in a magnetic ground state, you can enforce it e.g. with NUPDOWN and verify that it has a lower energy. Occasionally standard DFT also is not able to localize magnetic moments, in which case you could use LDA+U or hybrid functionals.

[hongyang_ma]

Thanks! Yes, after fixing the atomic spin by NUPDOWN, a much more reasonable hyperfine constant shows up.

[martin.schlipf]

Just keep in mind that you're not calculating the DFT ground state when you fix NUPDOWN. If you were to release the constraint, the system probably reverts to the unpolarized state. So you want to study the impact that NUPDOWN has on your result or find a good justification for the particular value you use.