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!
! Spectra correction tool by Oana Bunau and Matteo Calandra, Agust 2015
!
! This small code allows to
!
! 1) Remove states below a certain energy from the spectrum
! In large gap insulator it should work as the usual
! cut_occupied_states option but it is much much faster
! In metals/semimetals the normal and more time consuming
! option cut_occupied_states=.true. used in XSpectra
! should work better. The procedure use here can sometimes
! work for metals but care is needed.
!
! 2) For L23 edges, this code generates the full L23 spectrum from
! the L2 edge only. the L3 edge is obtained multiplying by two the
! L2 and shifting it by the spin-orbit splitting between 2p1/2
! and 2p3/2. Thus the spectrum in input must be the L2 edge.
!
! 3) Convolute a given spectrum known on a regular energy grid with
! a constant lorentz brodening gamma_hole, or with an atan
! broadening. In more details (s_in, s_out are cross sections):
!
! s_out(W)=integral s_in(om)*Gamma(W)/(Gamma(W)**2+(om-W)**2)/pi
!
! and the integral is over all the space (-infty, infty).
!
! If conv_type='lorentz' then Gamma(W)=gamma_hole constant
!
! If conv_type='lorentz_atan' then
! Gamma(W)=gamma_hole for W < xe0
! =Gamma_MAX*(0.5+atan(e-1/(e*e))) otherwise
! where e=(W-xe0)/(Ectr-xe0)
! and Ectr is the inflection point of the atan and xe0 is
! the pre-edge onset.
! For the definition of e see Eq. 7 and below in
! O. Bunau and M. Calandra, PRB 87, 205105 (2013)
!
! Finally emin_conv, emax_conv and nenergy_conv define
! the energy grid of the convoluted spectrum (energies labeled W above).
! If omitted, the energy grid is the same as in the input cross section.
!
! Important, please note that the convolution adds on TOP of the
! width of your original spectrum. So you should run xspectra with a
! tiny xgamma.
!------------------------------------------------------------------------------------
! How to use:
!
! 1) Use in single processor, no parallelization
!
! 2) Input file description:
!
! case (i): removal of occupied states from the spectrum
!
! &input_manip
! cross_section_file='xanes.dat',
! option='cut_occ_states',
! xe0=13.0,
! shift_spectrum=.false.,
! &end
!
! if shift_spectrum=.true. the spectrum is shifted in xe0
!
! case (ii): removal of occupied states from the spectrum
!
! &input_manip
! cross_section_file='xanes.dat',
! option='add_L2_L3',
! element='Cu',
! &end
!
! element is used to read the spin orbit splitting 2p1/2, 2p3/2
!
! The cross_section_file is the xanes.dat file with the cross section.
!
! case (iii) - lorentz
!
! &input_manip
! cross_section_file='xanes.dat.L23',
! option='convolution',
! shift_spectrum=.false.,
! element='Cu',
! conv_type='lorentz',
! gamma_hole=1.0,
! emin_conv=-50.0,
! emax_conv=100.0,
! nenergy_conv=1000,
! &end
!
! emin_conv, emax_conv and nenergy_conv can be omitted
!
!
! case (iii) - lorentz_atan
!
! &input_manip
! cross_section_file='xanes.dat.L23',
! option='convolution',
! shift_spectrum=.false.,
! element='Cu',
! conv_type='lorentz_atan',
! gamma_hole=0.05,
! gamma_max=6.0,
! ectr=-8.0,
! xe0=-19.0,
! &end
!
!
!
!----------------------------------------------------------------------------
|
