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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