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Re: comparing results of LDOS and XANES calculations

Hi John,
I guess that this recent thread leads me to a feature request. I often take the calculated LDOS and move it into another program where I can cut it with a Fermi function. It might be a useful to add a flag to the input file that would allow for the saving of the LDOS as calculated as well as both occupied and unoccupied LDOS. 

Jeff

Jeff Terry
Biological, Chemical, and Physical Sciences
Illinois Institute of Technology
Chicago IL 60616
phone 630-252-9708
fax       630-252-0358
http://mrmac.mr.aps.anl.gov/~jterry/


On Dec 7, 2004, at 7:42 PM, John J. Rehr wrote:


Hi Faisal,

  Thanks for your comments.
1. I am attaching the sum of all the p-symmetry LDOS as compared to the mu plot. Sorry that the axes are not labeled. The x-axis here is in electron volts. As you can see, there is significant disagreement between the pDOS and the mu plots, especially in the region of ~ 10 eV where there is no sharp p feature. Where is this feature in the mu plot coming from, if it is not present in the pDOS?
Except for the big peak at -10 eV which I don't understand either, there does seem to be a reasonable correspondence between the peaks. So I don't know which feature you are discussing. Perhaps it would help 
if you were to scale the pDOS so the pDOS and XAS are comparable in
magnitude. Also you should plot the matrix elements, col 2 vs 5 in
XMU.  The XAS is related to the pDOS by an energy dependent factor,
in brackets below:
mu(E) = mu_0(1 + chi(E)) = [mu_0(E)/rho_0(E)] rho (E) theta_Gamma(E-E_F)
2. In order to make a proper comparison between the pDOS and the mu functions, I suppose I need to add a step function to the pLDOS . Is that correct? Would it instead be valid to amplify the amplitude of the pLDOS 

  Yes - only the unoccupied DOS is related to the XAS. In the above
theta_Gamma(E-E_F) is a broadened step function.


   Could you please send me your feff.inp so I can understand better
what's going on e.g., at -10 eV?

   Thanks.
   J. Rehr