[Wien] Confusion regarding AFM structure of a spinel compound

[Laurence Marks]

Without the struct nobody can do more than guess.

My guess. In spinel you have any octahedral & tetrahedral sites. You put
one spin (Up) on octahedral sites, and the other (Dn) on tetrahedral. This
won't work.

_____
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what nobody
else has thought", Albert Szent-Györgyi
www.numis.northwestern.edu

On Mon, Jul 19, 2021, 03:23 shamik chakrabarti <shamik15041981 at gmail.com>
wrote:

> Dear Wien2k users,
>
>                     I was running AFM calculation of a spinel compound by
> flipping the spin in case.inst & by running spin polarize calculation.
> During structure optimization, the AFM structure appears well with zero
> moments per unit cell. However, when I have started an SCF by taking the
> optimized structure the calculation converges in 50 iterations with a
> moment ~ 8 muB/per unit cell. Also, the atoms which are connected with AFM
> ordering do not show equal moments with opposite directions. The moment of
> an atom is 2.7muB while the atom connected with AFM ordering showed a
> moment of -0.77  muB.
>
> The convergence criteria was set as: -ec 0.0001, -cc 0.0001, fc 1.0 &
> the calculation converges in 50 iterations.
>
> I have set 14 k-points for 56 atomic cells & also using GGA+U with U=6 eV
> for the TM atom.
>
> Any response in this regard will be helpful for us.
>
> Thanks in advance,
>
> with regards,
> --
> Dr. Shamik Chakrabarti
> Research Fellow
> Department of Physics
> Indian Institute of Technology Patna
> Bihta-801103
> Patna
> Bihar, India
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