questions from Bacewicz

[Bruce Ravel <ravel@phys.washington.edu>]

Hi all,

I received the following email and thought it was an appropriate
question for this list:

 RB> I have been using FEFF for quite a time now and it is a basic
 RB> tool for the XANES modelling for me. Recently I have been playing
 RB> with Mn impurity in different semiconductors and one of things I
 RB> am really interested in, is a charge state of Mn atom. From LDOS
 RB> results I got little bit strange numbers for the 3d state
 RB> occupation. My question is: how reliable is the code in such a
 RB> case? (by the way: how is the zero of energy point set in a LDOS
 RB> plot?)

 RB> Best regards			Rajmund Bacewicz
 RB> 					Faculty of Physics
 RB> 					Warsaw University of Technology

I would rather John or Alex comment on the reliability, but I think I
can answer the question of how the zero is set.

The self consistency loop works by integrating the densities of state
until the integrated area is equal to the number of valence
electrons.  This repopulates the electron occupancies for each type of
atom.  With repopulated atoms, the potentials are recomputed and the
densities are recomputed.  With recomputed densities, the integral is
performed again.  This loop is repeated until the densities converge.
The zero in energy is the Fermi energy, i.e. the energy at which the
integral equals the number of valence electrons in the final round of
the self-consistency loop.

Dr. Bacewicz, you might consider subscribing to the FEFFUSERS mailing
list.  Point your browser at
  http://feff.phys.washington.edu/feff/Notes_comments/feffusers.html
and follow the instructions.

B


-- 
 Bruce Ravel  ----------------------------------- ravel@phys.washington.edu
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