[Wien] txspec

[Joo Yull Rhee]

Thanks, Dr. P. Blaha.

I still do not understand.

L2-edge spectrum is SUM of 2p_1/2 -> d (l+1) transition and 2p_1/2 -> s (l-1) transition. The same is also true for the L3-edge, SUM of 2p_3/2 -> d (l+1) transition and 2p_3/2 -> s (l-1) transition.

In 'txsepc.f' the l -> l+1 transition is calculated first and stored into 'X(I,1)'. Then the l -> l-1 transition is calculated and stored into 'X(I,2)'. These two transitions have nothing to do with the L2- or L3-edge. As I told you, both edges contain these two transitions. The sum of X(I,1) and X(I,2) is stored into new variable X(I) and another new variable is introduced, XINTER(I). XINTER(I)=0 untill I=JEMIN+ISPLIT-1 and XINTER(I)=X(I) for I=JEMIN+ISPLIT to I=JEMAX+ISPLIT. Later XOUT(I)=XINT1*X(I)+XINT2*XINTER(I) is performed for I=JEMIN,JEMAX+ISPLIT. FInally, energy, XOUT(I), X(I,1) and X(I,2) are printed out. So, I think the SPLIT can 'split' the 2p_1/2 -> d (l+1) transition and 2p_1/2 -> s (l-1) transition, not the L2- and L3-edges.

Another question. How come the L2- and L3-edge spectra are identical to each other? Experimentally, they ARE different from each other. Theoretically, they should be different. Maybe the radial wave functions are not much different from each other, however, there are quite large difference in the occupation of states with different angular momentum (l) and its z-comp (m) quantum number. Therefore, it should make, at least, some difference in the dipole transition matrix elements.

One more question. Is the program 'txspec' treated the m-selection rule properly? I mean, since the incident light is usually not polarized, we have to consider all three possibilitites, delta_m=+1,-1,0. The first two transitions correspond to the right and left cirularly polarized lights and they are very important to MCD and to calculate the magneto-optic effect in ordinary optical conductivity calculation.

Joo Yull Rhee


-----Original Message-----
From: wien-admin at zeus.theochem.tuwien.ac.at [mailto:wien-admin at zeus.theochem.tuwien.ac.at]On Behalf Of Peter Blaha
Sent: Monday, August 18, 2003 3:54 PM
To: wien at zeus.theochem.tuwien.ac.at
Subject: RE: [Wien] txspec


> I am talking about the SO splitting of core level, not about the SO splitting of valence states. Pt 2p-level, for example, splits into 2p_1/2 and 2p_3/2 due to the SO coupling and the transitions from 2p_1/2 level to empty states above the Fermi level corresponds to the L2-edge spectrum and the transitions from 2p_3/2 level to the L3-edge spectrum. Therefore, for Pt the L2- and L3-edges are split
> by about 1730 eV.

In pure dipole approximation !! the L2 and L3 spectra are "identical" in
shape (neglecting the slightly different form of the 2p1/2 and 3/2 wf and
thus slightly modified matrixelements) and only "splitted" in energy (in
Pt aparaently by 1730 eV). This SPLIT can be mimicked by the SPLIT
parameter of TXSPEC, but since the split is so large (your spectra are
probably only 10-20 eV wide) it makes no sense to include this directly.
As I said, it is usefull only, when the core states are split only by a
few eVs and the L2 and L3 spectra thus overlap.

>  for the Pt 2p level the angular momentum quantum number is already fixed
>  (l=1), there are only two possible transitions: to l=2 (d-states) and
>  to l=0 (s-states). I think that the program 'txspec' can split these
>  two transitions, but not for the L2- and L3-edges. And I do not think
>  'SPLIT' can differentiate the L2- and L3-edges, either. I think the
>  parameter 'SPLIT' can do distinguish the l -> l+1 tanstion and l -> l-1
>  transition only. So, if the program 'txspec' uses only 'l' qunatum
>  number without differentiating the L2- and L3-edges, the resultant
>  spectrum is the sum of L2- and L3-edge spectra. Am I correct?

The resulting spectrum is calculated only for one type (I'm at the
moment not sure which core state is actually used, probably p3/2)
since these two spectra are the "same" (see above)) and are well seperated
in energy.

Of course the spectra are the sum of the l+1 and l-1 transitions (and you
can plot both contributions individually), but this has NOTHING to do with
the SPLIT parameter.

Regards
                                      P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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