Dear Gerhard
One clarification is needed I think. The discussion was about applying
an external ELECTRIC field (not a magnetic one).
Thus one part of your answer concerns something else which is also
interesting :) Indeed, my PhD student has written a modification of
WIEN2k to take into account the effect of an external magnetic field and
we are testing this new version with Peter and Pavel at this moment.
Happy new year to you Gerhard
Xavier
Le 03/01/2018 à 14:24, Fecher, Gerhard a écrit :
Dear Stefaan,
I am not realy sure what difference you expect,
I do not see why at two seemingly same surfaces the size of the magnetic moment
(orbital or spin) should depend on their orientation in the sense that it is
parallel or antiparallel to the surface normal.
I wonder about the interpretation where the magnetic moment points to (in an
absolute sense), if you change from 001 to 00-1 then the sign of the magnetic
moment does not change,
however, if you change the sign of the magnetisation from m to -m (instgen)
then the quantisation axis and the magnetisation may not longer be parallel
(the different situations are found in case.scfdmup).
The same might happen when applying an external magnetic field, it seems that
it is never checked that all quantisation axes are consistent,
that means it is not checked whether m or H parallel or antiparallel to the SO
quantisation axes,
without SO it seems that H doesn't change the symmetry at all (!?).
If there is a difference in the wave functions it may be only in the sign of
the phase such that it is lost in all cases where you use the absolute square.
Such differences in the phase enter effects that depend on the interferrence of
waves as appear in all kinds of circular dichroism, you will not see them in
pure intenities (square of wave functions but only in differences, what reminds
me on Jaroslavs recent questions before X-mas).
Analysing the wave functions one needs to have a look on the spinors.
Note that only s up, s down correspond to |1/2,1/2>, |1/2, -1/2> ==> mj = ml +
ms is either 0+1/2 or 0-1/2 because of ml=0 if l=0
for all higher angular momenta (l>0) mj = ml + ms may be reached by differen
spin orientation e.g. mj = 3/2 = 1+1/2 = 2-1/2 (here you may have ml=0, 1, 2 for
l=2)
The situation becomes worth if the quantisation axis is not along z (001, 00-1)
but along x or y,
in the latter case one either needs to rotate the wave functions (leading to
numerical issues) or one has additional off-diaogonal terms in the coupling
matrices.
(note that the treatment in the ncm version of Wien2k differs from the regular
one)
Coming back to my starting point, just something that will be different: If you
think about XMCD then you have to change the direction of photons to hit the
two different surfaces.
(and this might reverse the circular polarisation and thus the XMCD)
Ciao
Gerhard
DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."
====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien [[email protected]] im Auftrag von Stefaan
Cottenier [[email protected]]
Gesendet: Mittwoch, 3. Januar 2018 12:26
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] zigzag potential interpretation
Provide a indmc file as for lda+u (d-states and 0 0 at the end)
OK, done that, and now I see the vectorial information. Which confirms the same
picture as ever before: these two surfaces are fully equivalent. The question
remains: why...?
:ORB001: ORBITAL MOMENT: 0.00000 0.00000 0.09334 PROJECTION ON M 0.09334
:SPI001: SPIN MOMENT: 0.00000 0.00000 3.00530 PROJECTION ON M 3.00530
:ORB002: ORBITAL MOMENT: 0.00000 0.00000 0.09334 PROJECTION ON M 0.09334
:SPI002: SPIN MOMENT: 0.00000 0.00000 3.00531 PROJECTION ON M 3.00531
Stefaan
On 01/03/2018 12:02 PM, Stefaan Cottenier wrote:
Run x lapwdm -so -up
and look at the spin and orbital moments (vectorial) of the atoms there.
Hello Peter,
See underneath. I don't see vectorial information in there. The two atoms
shown are the 'left' and 'right' surface (i.e. with moments pointing into the
bulk and into the vacuum), and the two orbital moments are exactly identical
(consistent with sgroup/initso, which would have made these two surfaces
equivalent right away). Which is what I don't understand.
Stefaan
Spin-polarized + s-o calculation, M|| 0.000 0.000 1.000
Calculation of <X>, X=c*Xr(r)*Xls(l,s)
Xr(r) = I
Xls(l,s) = L(dzeta)
c= 1.00000
atom L up dn total
irtest 1 1 2.2199999999999989
:XOP001 0 0.000000 0.000000 0.000000 0.000000
:XOP001 1 -0.001531 0.001217 -0.000313 0.000000
:XOP001 2 -0.010694 0.104042 0.093349 0.000000
:XOP001 3 -0.000044 -0.000228 -0.000274 0.000000
:XOP001 4 0.092763 total
irtest 1 2 2.2199999999999989
:XOP002 0 0.000000 0.000000 0.000000 0.000000
:XOP002 1 -0.001531 0.001217 -0.000313 0.000000
:XOP002 2 -0.010694 0.104043 0.093349 0.000000
:XOP002 3 -0.000044 -0.000228 -0.000274 0.000000
:XOP002 4 0.092763 total
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