# CORRECTIONS

### From FEFF

* Useful *

CORRECTIONS vrcorr vicorr

The real energy shift vrcorr moves *E*_{0} in the final and the imaginary energy shift vicorr adds broadening
to the result. The real energy shift is useful to correct the error in FEFF’s Fermi level estimate
and the imaginary part can be used to correct for experimental resolution or errors in the
core-hole lifetime.
This error in the Fermi level is typically about 1 eV with
self-consistent calculations and about 3 eV with overlapped atom potentials. The imaginary
energy is typically used to correct for instrument broadening or as a correction to the mean
free path calculated by feff. This affects only the modnule FF2CHI, which combines the
results in all of the ‘feffNNNN.dat’ files. This card is useful in fitting loops because you can
simply make such energy corrections and see the results without redoing the entire XAFS
parameter calculation. CAUTION: the results are not as accurate as those obtained with the
EXCHANGE card. Both energies are in eV.

* Reduce E0 by 3.0 eV and add 1 eV of broadening (full width) * This will only affect module 4, ff2chi CORRECTIONS 3.0 1.0 real shift, imag shift