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

[Peter Blaha]

Yes, it is arbitrary what to specify up/dn in case.inst and you can swap it.

The orbital moment is just the sum_l ( sum_m ( m . q_lm ))

In other words: for a TM, you check the m=-2, -1, 0,1,2  partial 
charges, multiply it with the corresponding m and sum up.


Am 13.10.2024 um 12:35 schrieb pluto via Wien:
> 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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-- 
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Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-158801165300
Email: peter.blaha at tuwien.ac.at
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