[Wien] Choice of magnetization axis in the case with spin-orbit coupling

[Zhu, Jianxin]

Dear Xavier,

Thanks a lot for the suggestion.
When we say "such a direction is perhaps experimentally known" and "we impose a given direction in real-space for the magnetic moment  moments when we specify the (h k l) direction", do the magnetic moment mean the total magnetic moment, which is the sum of spin and orbital moments?
In my system, we have a significant contribution of orbital moment, which is even larger than the spin moment.

Best,

Jianxin

From: Rocquefelte <Xavier.Rocquefelte at cnrs-imn.fr<mailto:Xavier.Rocquefelte at cnrs-imn.fr>>
Organization: IMN Nantes
Reply-To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at<mailto:wien at zeus.theochem.tuwien.ac.at>>
Date: Tuesday, July 29, 2014 9:38 AM
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at<mailto:wien at zeus.theochem.tuwien.ac.at>>
Subject: Re: [Wien] Choice of magnetization axis in the case with spin-orbit coupling

You must try different directions in order to find the magnetization
easy axis.
Such a direction is perhaps experimentally know in your case. Thus you
can check by considering few crystallographic directions.

Should I always use positive values for (h k l)?
Or should I choose (0 0 1) when I prepare the spin moment to be up, that
is, during the stage of "instgen_lapw -ask"


The answer is no. The spin sign (up/down) has no relationship with the
direction of the magnetic moment.
You are just imposing a given direction in real-space for the magnetic
moments when you specify the (h k l) direction.

Cheers

Xavier



Le 29/07/2014 16:04, Zhu, Jianxin a écrit :
Dear Peter and Wien2k users,

For the spin-orbit case, when we run initso_lapw, we are prompted to
choose the moment direction

---->Please select the direction of the moment ( h k l )

I notice that the choices of e.g.,  (0  0  1) and (0  0  -1) give slight
different values.
In particular, when I choose (0  0  1), I obtain from LDA+U+SO

:MMINT: MAGNETIC MOMENT IN INTERSTITIAL =   -0.32640
:MMI001: MAGNETIC MOMENT IN SPHERE   1    =   -4.71648

:ORB001:  ORBITAL MOMENT:  0.00000  0.00000  4.59939 PROJECTION ON M
4.59939

while with (0 0 -1), I obtain from LDA+U+SO with the rest of conditions
the same

:MMINT: MAGNETIC MOMENT IN INTERSTITIAL =   -0.34861
:MMI001: MAGNETIC MOMENT IN SPHERE   1    =   -4.72342


:ORB001:  ORBITAL MOMENT:  0.00000  0.00000  4.52838 PROJECTION ON M
-4.52838


Should I always use positive values for (h k l)?
Or should I choose (0 0 1) when I prepare the spin moment to be up, that
is, during the stage of "instgen_lapw -ask"
select spinpolarization up, dn or non-magnetic ( u, d, n )
u

while (0 0 -1) when I prepare the spin moment to be down, that is, during
the stage of "instgen_lapw -ask"
select spinpolarization up, dn or non-magnetic ( u, d, n )
d


I appreciate if you can share your thought.



Thanks,

Jianxin

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