Re: Double core-hole

[Maurizo Mattesini <Maurizio.Mattesini@fysik.uu.se>]

Dear all

I have a question concerning the simulation of the 1s double core-hole 
in Li (for example). According to the last John Rehr's
e-mail I tried to edit the subroutine getorb and change the following lines

data (iocc( 3,i),i=1,29) /2,1,0,0,0, 0,0,0,0,0, 0,0,0,0,0, <----- Li 1s2 2s1
1 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0/
data (ival( 3,i),i=1,29) /0,1,0,0,0, 0,0,0,0,0, 0,0,0,0,0,
1 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0/
data (ispn( 3,i),i=1,29) /0,1,0,0,0, 0,0,0,0,0, 0,0,0,0,0,
1 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0/

into

data (iocc( 3,i),i=1,29) /1,1,0,0,0, 0,0,0,0,0, 0,0,0,0,0, <----- Li 1s1 2s1
1 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0/
data (ival( 3,i),i=1,29) /0,1,0,0,0, 0,0,0,0,0, 0,0,0,0,0,
1 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0/
data (ispn( 3,i),i=1,29) /0,1,0,0,0, 0,0,0,0,0, 0,0,0,0,0,
1 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0/

and then I have recompiled the program. Now, as far as I understand the 
calculation of the XANES for the 1st case
will simulate the Li K-edge with a single 1s core hole, providing the 
use of the card HOLE=1. That is, the z+1 approximation
will emulate the 1s1 2s1 configuration. By analogy, the 2nd case should 
therefore simulate the double 1s core-hole (e.g., 1s0 2s1).
Is this procedure correct? I'd really appreciate any comments on this. 
Furthermore, which is the right way to follow
the electronic charge redistribution on the absorber atom and around its 
1st coordination shell?

Best regards,
Maurizio


John J. Rehr wrote:

> Dear Maurizio,
>
>  This is an interesting question.  For deep double-core hole excitations
> one can do this with a little recoding. Namely you have to modify the entries
> in subroutine getorb (do a search on ine getorb) and by hand alter the
> entries for the particular level you want to be the 2nd hole.  Then
> recompile and run. The absorption should then be that for a 2 core hole
> state. The excitation energies won't be right, but you can align the
> results to experiment. It's not something for a novice user, unfortunately.
>
>  Please let me know if you have difficulty doing this and we can
> assist e.g., for some sample double hole state.
>
>  Similar modification of getorb can be used to deal with fractional
> core hole states. This has also been done many times.
>
> With best wishes,
>  John Rehr
>
>
>