[Pw_forum] hyperfine calculation

[Gregor Mali]

Dear Jones Wan 

> 
> HF of Si:
> 
>  Si   1: g_n = -1.110574                  MHz
>  Si   1  hfi_dipole       0.000000       0.000000       0.000000
>  Si   1  hfi_dipole       0.000000       0.000000       0.000000
>  Si   1  hfi_dipole       0.000000       0.000000       0.000000
> 
>  Si   1  hfi_dipole       0.000000       0.000000       0.000000
> 
> Fermi contact term:        bare     reconstruction      total
>                          0.000000      45.266354      45.266354
>  **** ZORA ****
>                          0.000000      42.470825      42.470825

So far I've never obtained dipole coupling equal to zero! Are you sure
that there are no mistakes in your spin-polarized scf calculation?

(For example, the materials that I study are paramagnetic at room
temperature, and antiferromagnetic at low temperature. However, if I
want to obtain information on hyperfine coupling related to the
paramagnetic state, I start with ferromagnetic arrangement of spins.
This arrangement more accurately resembles the state of my material at
room temperature and strong external magnetic field.
I mention this because one reason for zero dipole term might be
antiferromagnetic arrangement of spins. In such an arrangement
contributions of neighbouring spins to dipole tensor could cancel one
another.)
 
Best regards.

Gregor

Gregor Mali
National Institute of Chemistry
Ljubljana, Slovenia