[Wien] Using constant orbital potential with S-O Coupling

[David Tompsett]

Dear All,
             I am attempting to investigate an Yb based system where I 
wish to effectively shift the f-levels by using a constant orbital 
potential.

I have attempted to use a similar prescription to that in a previous 
email from P. Novak:

"Dear Yongbin,

you can influence the hybridization by changing relative positions of
3d(Fe) and 5d(Gd) bands. If they will be well separated, hybridization
will be small, if their centers coincide, hybridization will be maximal.
To proceed, look first in the DOS projected on 3d(Fe) and 5d(Gd) states
and decide how you would like to shift them. Then use the command
runsp_lapw -orbc
that adds constant orbital potential acting on selected states of selected
atoms. First you have to construct by hand the orbital potential files
gdfe2.vorbup, gdfe2.vorbdn
these will have nonzero diagonal elements equal to the shift and zero
nondiagonal elements. Attached you can find an example of .vorbup for a
compound with two types of atoms, constant potential -0.2 H is added for
d-states of the 1st atom and +0.2 H for d-states of 2nd atom.

Regards
Pavel Novak"

Essentially, I wish to have some control over the f-valence of my material with 
such a shift. I am running with 
runsp_lapw -orbc -so

My .vorbup file was contructed to look like (The matrix is 7x7 for an f orbital):
  1  1  1  0.000000E+00 nmod, nsp, natorb, muB*Bext (Ry), spin up  
           5           1  atom type, number of L
   3 AMF   5.0000   0.0000 L, modus, U, J (Ry)
   0.2000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.2000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.2000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.2000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.2000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.2000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.0000000000000   0.0000000000000
   0.2000000000000   0.0000000000000

My .vorbdn is identical except that nsp=-1.


My question relates to some confusion about the output. I though that 
with SO coupling the spin up and spin down eigenstates are equivalent 
eg, band 89 and 90 are the same. But in my output they are clearly 
different. My orbital potential is affecting the two channels 
differently and I don't understand why?

I looked at the notes in P. Novak's chapter on orbital potentals where 
it says eq. 4:
Ecorr = Eorb - Tr(Vorb, n).
Are the two spin channels affected differently due to different 
occupation numbers, n?

Thank you for any help,
David.

-- 
David A. Tompsett
Quantum Matter Group
Cavendish Laboratory
J. J. Thomson Avenue
Cambridge CB3 0HE
U.K.
Tel: +44 7907 566351 (mobile)
Fax: +44 1223 768140
http://www-qm.phy.cam.ac.uk/