[Ifeffit] odd behaviour in the lDOS of GeO2

Andreas Schacht schacht at physik.uni-dortmund.de
Wed May 3 10:28:13 CDT 2006


Dear helper team,

i was trying to calculate the XANES spectra for alpha-quartz GeO2. The
principle problem seems to be, that the fermi energy in the
lDOS-calculations seems to be completetly wrong. If i look at the
xanes-spectra with this fermi-energy the spectra does not fit with any
experiment.
In my opinion the fermi level should be shifted approximately by -18ev or
so. If I try to fix the problem by simply adding an exchange energy in the
feff.inp that does not give any better results so it would be very
helpfull if someone can help me, perhaps having the same problems with
totally wrong fermi-levels.

additionally I give you my feff.inp file for the GeO2. And of course the
atoms list consists of about 160 atoms but I omit them here.

Thanks for any help



 * This feff8 input file was generated by WebAtoms 1.8 (Atoms 3.0beta10)
 * Atoms written by and copyright (c) Bruce Ravel, 1998-2001

 TITLE GeO2 alpha

 * This feff8 input file was generated by WebAtoms 1.8 (Atoms 3.0beta10)
 * Atoms written by and copyright (c) Bruce Ravel, 1998-2001

 TITLE GeO2 alpha

 *  Ge K edge energy = 11103.0 eV
 EDGE      K
 S02       1.0

 *         pot    xsph  fms   paths genfmt ff2chi
 CONTROL   1      1     1     1     1      1
 PRINT     1      0     0     0     0      0

                          *** ixc=0 means to use Hedin-Lundqvist
 *         ixc  [ Vr  Vi ]
 EXCHANGE  0

                          *** Radius of small cluster for
                          *** self-consistency calculation
                          *** A sphere including 2 shells is
                          *** a good choice
                          *** l_scf = 0 for a solid, 1 for a molecule
 *         r_scf  [ l_scf   n_scf   ca ]
 SCF       5.0

                          *** Upper limit of XANES calculation.
                          *** This *must* be uncommented to
                          *** make Feff calculate full multiple
                          *** scattering rather than a path expansion
 *         kmax   [ delta_k  delta_e ]
 XANES     4.0

                          *** Radius of cluster for Full Multiple
                          *** Scattering calculation
                          *** l_fms = 0 for a solid, 1 for a molecule
 *         r_fms     l_fms
 FMS       8.0  0

                          *** Energy grid over which to calculate
                          *** DOS functions
 *         emin  emax   eimag
 LDOS      -30   20     0.1

                          *** for EXAFS:  RMAX   8.0 and uncomment
                          *** the EXAFS card
 RPATH     0.1
 *EXAFS     20

 POTENTIALS
 *    ipot   Z  element            l_scmt  l_fms   stoichiometry
        0   32   Ge                 2       2       0.001
        1   32   Ge                 2       2       3
        2    8   O                  1       1       6

 ATOMS                          * this list contains 163 atoms
 *   x          y          z      ipot  tag           distance
    0.00000    0.00000    0.00000  0    Ge1           0.00000     0
    1.53968   -0.61764    0.51379  2    O1            1.73668     1
    0.23495    1.64222   -0.51379  2    O1            1.73668     2
   -1.06503   -0.14213    1.37021  2    O1            1.74125     3
...




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