[Wien] Magnetic anisotropy energy

[Peter Blaha]

No, for the SO calculations you should NOT use runsp

As I said, we obtain the MAE from NON-scf calculations (force theorem, I 
guess it is from O.Anderson).

On 09/25/2013 09:13 AM, Madhav Ghimire wrote:
> Dear Prof. Blaha,
>      Thank you very much for the good response.
> It helps a lot. I follow the pattern as per your suggestions.
> The jobs are submitted.
> However, I have sligt confusion whether I have to use "runsp_lapw -orb
> -so -p -ec 0.000001"
> So, Could you please confirm if I am on the right track:
>
> (i) Choose a symmetry, in which both magnetization directions can be
> described (maybe even P1).
>  >>> I created the new structure file [P] of 20 atoms from the original
> structure [P21/n] file of 6 atoms in a unit cell
>
> (ii) runsp -ec 0.000001     with VERY good k-mesh (SO anisotropy is VERY
> sensitive to k-mesh)
>  >>>  runsp_lapw -orb -p -ec 0.000001
>
> (iii)  M in (001) in case.inso
> x lapwso -up
> x lapw2 -up -so
> x lapw2 -dn -so
> add the two "sum of eigenvalues" energies at the bottom of scf2up/dn
>
>  >>> After convergence of runsp_lapw step, I will generate case.inso for
> M in (001) using initso_lapw
> Then, shall I run  "runsp_lapw -orb -so -p -ec 0.0000001" before starting
> x lapwso -up
> x lapw2 -up -so
> x lapw2 -dn -so
> or I can directly run these commands as you described ?
>
> (iv) M in (100) direction; and repeat the above steps.
> The difference of these energies gives you the MAE.
>  >>> Same clarification needed for this steps
>
> With thanks
> Madhav Ghimire
>
>
>
> On Wed, Sep 25, 2013 at 2:32 PM, Peter Blaha
> <pblaha at theochem.tuwien.ac.at <mailto:pblaha at theochem.tuwien.ac.at>> wrote:
>
>     I would not do it with scf calculations, but using the "force theorem".
>
>     Choose a symmetry, in which both magnetization directions can be
>     described (maybe even
>     P1).
>     runsp -ec 0.000001     with VERY good k-mesh (SO anisotropy is VERY
>     sensitive to k-mesh)
>
>     M in (001) in case.inso
>     x lapwso -up
>     x lapw2 -up -so
>     x lapw2 -dn -so
>     add the two "sum of eigenvalues" energies at the bottom of scf2up/dn
>
>     M in (100) direction; and repeat the above steps.
>     The difference of these energies gives you the MAE.
>
>     Papers: I don't know without checking, but there should be several
>     papers by Igor Mazin
>
>
>     Am 24.09.2013 10 <tel:24.09.2013%2010>:53, schrieb Madhav Ghimire:
>
>         Dear Prof. Blaha and wien users,
>
>         I tried to calculate the magnetic anisotropy energy (MAE) of
>         double-perovskites A2BB'O6 with magnetic ions in A (lanthanides)
>         and B' (transition metals) sites.
>         Following the definition and methods given in Phys. Rev. B 65
>         134422, i obtain the MAE using
>         E=E(001)-E(100)
>         which is un-expectedly large (~ 1.0 eV)
>         I would be glad to get your opinion:
>         (i) In Wien2k, Can we calculate MAE as the total
>         energy-difference between E(easy axis magnetization) and E(hard
>         axis) or need additional term to include
>         (ii) Any relevant paper discussing about MAE based on Wien2k
>         calculations
>
>         Thanks
>
>         Madhav Ghimire
>
>         --
>         MANA, Nano-System Theoretical Physics Unit
>         NIMS, Tsukuba, Japan
>
>
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>     --
>     ------------------------------__-----------
>     Peter Blaha
>     Inst. Materials Chemistry, TU Vienna
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> NIMS, Tsukuba, Japan
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                                       P.Blaha
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