[Wien] When to apply the SOC and when not to apply SOC in the calculation?

[Peter Blaha]

Hm, I don't know if I understand everything. There's no rare-earth element in your
compound ???

Anyway:

Yes, for practically all 3d- transition metal oxides (Cu, Co-oxide like yours) going
beyond stadard DFT is necessary. LDA+U is the "simplest" of these methods and quite
good for these systems. In addition, magnetism (FM or more likely some AFM configuration)
needs to be considered.

SOC: The effects of SOC are usually larger for heavier elements, like 5d-series or 5f actinides.
Nevertheless, in particular together with magnetism (orbital moments) even for 3d-elements
(Co is famous for this) it can sometimes be an important ingredient, but usually SOC does not
change the results for 3d-systems qualitatively, but only quantitatively

For rare-earth systems, usually LDA+U is "more important" than SOC, but of course also SOC
can be important (again, in particular for magnetism).

These are just rough guidelines. One never knows for a particular system unless one tries it ....

Am 11.08.2012 07:04, schrieb Qiwen:
> Dear Wienk developers and users,
>
> I recently done the calculations to this compound SrCuCoO4 - it is a double perovskite hexagonal (I4/MMM) ceramic, with weak ferromgantic/antiferromagnetic property.
>
> I did only the spin polarized calculation as a part of the content for a paper. Upon submitting the paper to a journal, a feedback to the calculation part was saying that I
> didn't treat the Spin Orbit coupling and the correlation effects in the calculation as I should for rare-earth elements in DFT calculation.
>
> This makes me think of the 2 question:
> 1.　when is it appropriated to apply the SOC and when does it not needed in the calculation?
>
> ２. Was the feedback correct that for all rare-earth element related semiconductor compounds we have to apply the SOC and the +U(for the correlation) even if it is not a
> correlated system?
>
> I could only find previous discussion on how to apply SOC and/or LDA+U but not when to apply so please pardon me if similar question have been answered before.
>
> Thank you very much for your time.
>
> kind regards,
> Wen
>
>
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-- 
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Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
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