[Pw_forum] SiO2 xanes calculation

[maxradin at umich.edu]

Hi,

I'm trying to repeat the ultrasoft core-hole calculation of the Si K-edge
in Matteo's paper:

"First-principles calculations of x-ray absorption in a scheme 
based on ultrasoft pseudopotentials: From alpha-quartz to 
high-Tc  compounds"

I haved used the same parameters given in that article (cell size, cutoff
energies, kpoints) but the spectrum that I get does not at all look right.
Is it possible that this discrepancy is due to the choice of
pseudopotentials? For the absorbing atom I am using 

http://www.quantum-espresso.org/pseudo/1.3/UPF/Si.star1s-pbe-van_gipaw.UPF

which I think is the same one used in the paper. For the other atoms I am
using the ultrasoft pseudopotentials included with the xspectra SiO2
example (Si_PBE_USPP.UPF and O_PBE_USPP.UPF).

Also, I obtained the fermi level from the output of the scf calculation
(converted from eV to Ry). Is this the correct way to choose the ef_r
parameter? My input files are attached.

Regards,

Max 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: SiO2.scf.in
Type: text/plain charset=us-ascii
Size: 5772 bytes
Desc: not available
Url : http://www.democritos.it/pipermail/pw_forum/attachments/20110706/f6fc6f21/attachment.bin 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: SiO2.xspectra_dip_plane.in
Type: text/plain charset=us-ascii
Size: 625 bytes
Desc: not available
Url : http://www.democritos.it/pipermail/pw_forum/attachments/20110706/f6fc6f21/attachment-0001.bin