[Wien] Fixed spin moment calculation combined with spin scaling xc

[Peter Blaha]

It was quite some time ago when I implemented the scaled Vxc.

I looked again into the paper by Mazin and I'm not completely sure about 
his nomenclature about E_xc^P. If I assume that this term is just our 
(E_x(up)+E_x(dn)) and my "E_c" is his f(chi)*delta epsilon_xc(n), then 
spin scaling for the energy is trivial by multiplying the E_c term with 
the scaling parameter s.

I've done this in the attached subroutine vxclm2.f in lapw0.

You may test it and see if it gives reasonable results. However, no 
tests from my side yet. (Test eg. a non-spin-polarized calc with or 
without spin-scaling must give identical E-tot)

Peter Blaha

On 05/16/2017 02:25 PM, Peter Blaha wrote:
> Yes and no.
>
> Technically I guess you can do it.
>
> However, the spin scaling is implemented only in the potential, i.e. the
> spin-scaling will reduce the spin-polarized Vxc and thus the magnetic
> moments. But with FSM you increase the EF-shifts, until the moment is
> what you like.
> Exc, which you usually need in an FSM calculation has not been
> implemented with spin.scaling in wien2k.
>
> One should check the paper of Mazin and see how this should be
> implemented. It should not be so difficult, but ...
>
> On 05/16/2017 12:30 PM, "Niedermayr, Arthur" wrote:
>> Hello,
>>
>> I would really appreciate it if somebody could tell me if*_a fixed spin
>> moment calculation combined with spin scaling_* is possible in WIEN2k.
>>
>> Best regards,
>> Arthur Niedermayr
>>
>>
>>
>>> -------- Original Message --------
>>> Subject: Fixed spin moment calculation combined with spin scaling xc
>>> Local Time: 5. Mai 2017 6:59 PM
>>> UTC Time: 5. Mai 2017 16:59
>>> From: a.niedermayr at protonmail.com
>>> To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
>>>
>>> Hello wien2k-users,
>>>
>>> I performed a LSDA calculation with spin scaling and got a reasonable
>>> value for my magnetization (the scf cycle converged, no errors). [1]
>>>
>>> But if I try to do it the other way around, i.e. if I perform a fixed
>>> spin moment calculation (with spin scaling parameter xc) for different
>>> magnetization values, then I don't get a minimum in the total energy
>>> at the received value of the magnetization in [1].
>>>
>>> My questions:
>>> *_Can I combine a fixed spin moment calculation with spin scaling?_*
>>> _If not, are there other possibilities to check the magnetization
>>> dependence of the total energy?_
>>>
>>>
>>>
>>>
>>> Best regards and thank you in advance!
>>> Arthur Niedermayr
>>
>>
>>
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>

-- 

                                       P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at/TC_Blaha
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