[Wien] magnetizatin direction in case.inso vs case.inst

[pluto]

Dear Prof. Blaha,

Thank you for very quick answer!

I understand that once I set the magnetization to [001] in case.inso, 
then the majority-spin will be aligned along [001].

This means that when I use instgen_lapw, every local moment that I set 
to "up" will be initially aligned along [001], and every local moment 
that I set to "dn" will be aligned along [00-1].

I understand that this initial configuration can change over the SCF 
cycles, but one can monitor this using "grep :MM case.scf".

I understand that the orbital moment is just a consequence of the above 
settings.

I have two follow-up questions:

- Is the direction of the majority/minority spin in instgen_lapw 
arbitrary? This would mean swapping all up/dn there would also 
effectively swap the directions of local moments along the M direction 
set in case.inso

- How is the orbital moment calculated?

Best,
Lukasz

PS: Some output of my converged calculation below. Sphere 1 is "up", 
sphere 2 is "dn", other spheres are non-magnetic. Orbital moment seems 
quite significant.

grep :MM case.scf
:MMINT:  MAGNETIC MOMENT IN INTERSTITIAL  =    0.69969
:MMI001: MAGNETIC MOMENT IN SPHERE   1    =    5.16649
:MMI002: MAGNETIC MOMENT IN SPHERE   2    =   -2.41664
:MMI003: MAGNETIC MOMENT IN SPHERE   3    =    0.10539
:MMI004: MAGNETIC MOMENT IN SPHERE   4    =    0.10587
:MMI005: MAGNETIC MOMENT IN SPHERE   5    =    0.11216
:MMTOT:  SPIN MAGNETIC MOMENT IN CELL     =   -7.98682

grep :ORB case.scf
:ORB001:  ORBITAL MOMENT:  0.00000  0.00000  1.62857 PROJECTION ON M  
1.62857




On 2024-10-13 09:36, Peter Blaha wrote:
> Many "No.no.no" ..., see below.
> 
>> I would like to make a collinear magnetic+SOC calculation that 
>> simulates the sample magnetized in opposite directions along some easy 
>> axis. I am looking both at ferromagnetic and ferrimagnetic samples, 
>> where only some atoms are magnetic. Could you please tell me the 
>> correct procedure.
>> 
>> One can set the direction of magnetization in case.inso and in 
>> case.inst.
> 
> No, only in case.inso.
> Without SO, there is no coupling of the direction of the magnetic
> moment and the lattice.
> What you set in case.insp is the STARTING (can change during scf)
> SPIN-magnetic moment. But "up" means just "majority", and does NOT
> mean a "z-direction" with respect to your lattice.
> 
> 
>> One can see sizes of magnetic moments through:
>> 
>> grep :MM case.scf
> 
> These are only the spin-moments. In a SO calculation, you should add
> the orbital moments (check your scf file).
> 
> You can then also check the direction of the moments with respect to
> your quantization axis in case.inso.
> 
> I guess the above shoud have answered also the rest of your questions.
> 
>> 
>> How are all the three things (inso, inst, and scf) related?
>> 
>> I would assume that case.inso only sets the quantization axis (but 
>> does not physically change the directions of magnetic moments). 
>> Therefore, for two identical calculations but with inso at [001] and 
>> [00-1], the result should be exactly the same in energy, but the spin 
>> up/dn weights of orbital characters should be swapped. Spin-integrated 
>> (adding up+dn) weights of the Ylm orbitals should not change in such 
>> case.
>> 
>> But then what is the precise meaning of the u/d/n when producing the 
>> case.inst using instgen_lapw? Are those, for the SOC calculation, 
>> ultimately referring to the quantization axis set in case.inso? I 
>> mean, would setting "up" in case.inst mean the moment oriented in real 
>> space along the direction set by instgen_lapw in case.inso?
>> 
>> Also, what do the magnetic moments in case.scf mean? They have signs, 
>> so they must refer to some quantization axis.
>> 
>> Best,
>> Lukasz
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