[Wien] Clarification on (a) effective moment including spin-orbit coupling and (b) spin-state configuration

Kalpana kalpana.ghm at gmail.com
Thu Oct 3 04:28:07 CEST 2013


Dear Tran,
   Thank you very much. The studied system is not an insulator, rather it
is a metal with/without SOC.
As far as the integer moment is concerned, Half-metals also carries an
integer effective moment. Right?

So, should I stick to the conclusion that GGA+U and GGA+U+SOC calculations
should have the same :MMTOT.
If yes, I can see the clear difference between MMTOT by ~ 0.271 Bohr
magneton.
I am curious why this difference comes.

I was presuming that in GGA+U+SOC, the EFFECTIVE MOMENT = :MMTOT =  4.72942

Thus, in Wien2k, does it mean that we need to add the orbital term manually
with MMTOT. For example,  4.72942 + 1.57792 = 6.30734
If so, is there any script which gives us the effective moment including
orbital moment.

I will be very glad for your help in resolving this issues.
Best regards



On Wed, Oct 2, 2013 at 11:54 PM, <tran at theochem.tuwien.ac.at> wrote:

> As I said, :MMTOT is the number of up-electrons minus the number of
> down-electrons, which obviously means that orbital(L) is not included.
>
> If your system is an insulator, then :MMTOT is an integer
> (e.g., :MMTOT=23-18=5), but if it is a metal, then :MMTOT can be
> a non-integer (e.g., :MMTOT=22.8-18.2=4.6) because some bands are
> only partially filled.
>
>
>
> On Wed, 2 Oct 2013, Kalpana wrote:
>
>  Dear Prof. Blaha and Tran,    Thanks for your nice comment.
>> Your reply to my first and third questions in clear now.
>> However, I am still not clear to my first question.
>>
>> While performing the calculations for GGA+U and GGA+U+SOC, I obtained
>> solutions of total spin-magnetic moemnts as below:
>>       With GGA+U             ==== :MMTOT: SPIN MAGNETIC MOMENT IN CELL
>> = 5.00042
>>       With GGA+U+SOC  ==== :MMTOT: SPIN MAGNETIC MOMENT IN CELL   =
>> 4.72942
>>
>> (i) The MMTOT (Spin-magnetic moment) from GGA+U+SOC is 4.72942 not 5.00,
>> which I suppose to be same or nearly equal because both
>> are spin-magnetic moment in cell [without including spin-orbit coupling].
>> So, I am interested to know whether the SPIN MAGNETIC MOMENT in CELL for
>> GGA+U+SOC should be read as an effective moment [i.e.
>> spin(S) + orbital (L)] or something else.
>> Additionally, if they are the actual SPIN MOMENT in GGA+U+SOC, why are
>> their magnitude different with GGA+U because
>> orbital-moment is not included.
>> Can you please clarify my doubt again.
>> Thanks
>> Kalpana
>>
>>
>>
>>
>>
>>
>> On Wed, Oct 2, 2013 at 9:36 PM, Peter Blaha <pblaha at theochem.tuwien.ac.at>
>> wrote:
>>             (ii) When considering the GGA+U+SOC (spin-orbit coupling), I
>> find that
>>             the results on spin-magnetic moment in a cell significantly
>> changes with
>>             respect to GGA+U.
>>             For example,
>>             With GGA+U             ==== :MMTOT: SPIN MAGNETIC MOMENT IN
>> CELL   =
>>             5.00042
>>             With GGA+U+SOC  ==== :MMTOT: SPIN MAGNETIC MOMENT IN CELL   =
>>     4.72942
>>
>>
>> If you did not make any other mistake, it means that without SO you have
>> probably an insulating state, while with SO you
>> got a metal.
>>
>>       Co
>>       Ar 3
>>       3, 2,2.0  N
>> 3, 2,2.0  N   intermediate spin:    low spin
>> 3,-3,3.0  N      2.0                  1.5
>> 3,-3,0.0  N      1.0                  1.5
>> 4,-1,1.0  N
>> 4,-1,1.0  N--
>>
>>
>> But there is NO guarantee, that these starting configurations yield the
>> desired states.
>>
>> Evendually, you can manually modify the case.dmatup/dn files and run
>> -orbc   or for a FM you can use runfsm
>>
>> Peter Blaha
>> Inst.Materials Chemistry
>> TU Vienna
>> Getreidemarkt 9
>> A-1060 Vienna
>> Austria
>> +43-1-5880115671
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>>
>>
>>
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