XSPECTRA : X-ray spectra calculation

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by C. Gougoussis, M. Calandra, A. Seitsonen and F. Mauri

The theoretical approach on which XSpectra is based was
described in:

Christos Gougoussis, Matteo Calandra, Ari P. Seitsonen, Francesco Mauri,
"First principles calculations of X-ray absorption in an ultrasoft
pseudopotentials scheme: from $\alpha$-quartz to high-T$_c$ compounds",
Phys. Rev. B 80, 075102 (2009)

you should cite this work in all publications using this software.

If you use only Norm Conserving pseudopotentials, you should also
cite the following publication:

M. Taillefumier, D. Cabaret, A. M. Flank, and F. Mauri
"X-ray absorption near-edge structure calculations with the pseudopotentials: Application to the K edge in diamond and αalpha
-quartz"
Phys. Rev. B 66, 195107 (2002)

The implementation of the DFT+U approximation and its application to
K-edge XAS in NiO was performed in:

C. Gougoussis, M. Calandra, A. Seitsonen, Ch. Brouder, A. Shukla, F. Mauri
" Intrinsic charge transfer gap in NiO from  Ni K -edge x-ray absorption spectroscopy", Phys. Rev. B 79, 045118 (2009)


Finally you should cite properly the Quantum Espresso package.

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For more information about XSpectra read doc/INPUT_XSPECTRA
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This module uses subroutines from PW with the general infrasturcture provided by
Quantum Espresso. 

The directory XSpectra must reside immediately under the espresso directory for Makefiles to work. 

Standart compilation: Run "make xspectra" in espresso directory where XSpectra is a subdirectory
 
Directory Structure: 
src      : The source files
doc      : The documentation
examples :
tools    : small programms and scripts
           1) Plot core density for UPF pseudopotential format