Dear Stefaan
I reconsider more carefully your case.struct file.
Indeed, in your case you have 8 symmetry operations.
As mentionned by Laurence :
"The equivalence may be related to how -so is implemented, with an
implicit time-reversal for some symmetry operations. You may have to dig
through the code to see if the vector values being output are time
forward or backwards."
What you observe is certainly due to this aspect because point group of
the iron atoms in this cell is 4mm.
Cheers
Xavier
Le 03/01/2018 à 15:41, Xavier Rocquefelte a écrit :
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 [wien-boun...@zeus.theochem.tuwien.ac.at] im Auftrag von
Stefaan Cottenier [stefaan.cotten...@ugent.be]
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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